Optical communication system, optical communication device, control device, optical communication method, and optical communication control method

Abstract

To relay an optical signal transmitted from a subscriber device according to a destination by setting the subscriber device to be able to use a path according to the destination.SOLUTION: The optical communication system includes a control unit that communicates with a subscriber device using a control signal, an access control unit that permits main signal communication to the subscriber device, an add / drop unit that inputs an optical signal from the subscriber device and outputs an optical signal to the subscriber device, and a multiplexing / demultiplexing unit that concentrates an optical path from the subscriber device to the other path in an upstream direction and distributes an optical path from the other path to the subscriber device in a downstream direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an optical communication system, an optical communication device, a control device, an optical communication method, and an optical communication control method. This application claims priority to PCT / JP2019 / 051305 filed on December 26, 2019, PCT / JP2020 / 005782 filed on February 14, 2020, and PCT / JP2020 / 033760 filed on September 7, 2020, the contents of which are incorporated herein by reference. [Background technology]

[0002] The number of users using high-speed Internet via FTTH (Fiber To The Home) and mobile services continues to increase. High-speed Internet has become indispensable in people's lives. However, in backbone networks that provide FTTH and mobile services, networks are built independently for each service. This leads to operational inefficiencies. To address this issue, access networks that accommodate multiple services using a single device have been proposed (see, for example, Non-Patent Document 1). Furthermore, to realize access networks that can accommodate multiple services, passive optical networks (PONs) such as WDM-PON (Wavelength Division Multiplexing PON) and TDM-PON (Time Division Multiplexing PON), which use multiple wavelengths, have been standardized by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) (see, for example, Non-Patent Document 2).

[0003] On the other hand, in existing optical access systems, communication between subscriber-side devices and central offices is connected to a higher-level core network. The subscriber-side devices are, for example, optical network units (ONUs). Connection to the core network is made via a terminal device within the central office equipment. The terminal device is, for example, an optical line terminal (OLT). Optical access, which connects to the core network via packet switching, performs processes such as adding or deleting user information and destination information from signals and routing. When adding or deleting user information or destination information, optical signals may be converted to electrical signals. This causes a certain degree of delay in communication. Furthermore, when the data volume increases, signals may be stored in a buffer and priority control may be performed. This further increases the delay. Longer delays significantly degrade the quality of optical services. Therefore, it is important to minimize delays as much as possible.

[0004] To improve the quality of optical services and provide a variety of services over optical access networks, it is necessary to reduce the delay that occurs. Delay can be significantly reduced by using optical switches that can perform routing and other processes without converting optical signals into electrical signals. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Shunji Kimura,"Elastic Lambda Aggregation Network (EλAN) -Proposal for Future Optical Access Network-",2013 18th OptoElectronics and Communications Conference held jointly with 2013 International Conference on Photonics in Switching(OECC / PS),WP4-4,2013 [Non-patent document 2] "ITU-T G.989.1", International Telecommunication Union, 2013 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in routing using optical switches, it is necessary to set the route of the optical signal according to the destination of the subscriber device, and further to set (wavelength, etc.) the transmitter and receiver of the subscriber device.

[0007] In view of the above circumstances, the present invention aims to provide an optical communication system, an optical communication device, a control device, an optical communication method, and an optical communication control method that can set up a subscriber device so that a route according to the destination can be used, and relay an optical signal transmitted from the subscriber device according to the destination. [Means for solving the problem]

[0008] One aspect of the present invention is an optical communication system that performs optical transmission between subscriber devices and relays optical signals according to their destination, and includes a control unit that communicates with the subscriber device using control signals, an access control unit that grants permission for main signal communication to the subscriber device, an add / drop unit that inputs optical signals from the subscriber device and outputs optical signals to the subscriber device, and a multiplexing / demultiplexing unit that concentrates optical paths from the subscriber device to another path in the upstream direction and distributes optical paths from the other path to the subscriber device in the downstream direction.

[0009] One aspect of the present invention is an optical communication device that performs optical transmission between subscriber devices and relays optical signals according to their destinations, and includes a superposition unit that superposes a control signal onto a main signal for a control device to communicate with the subscriber device, an access control unit that grants permission for main signal communication to the subscriber device or grants the permission based on instructions from the control device, an add / drop unit that inputs optical signals from the subscriber device and outputs optical signals to the subscriber device, and a multiplexing / demultiplexing unit that concentrates optical paths from the subscriber device to another route in the upstream direction and distributes optical paths from the other route to the subscriber device in the downstream direction.

[0010] One aspect of the present invention is a control device that includes a control unit that communicates with a subscriber device using control signals so that the subscriber device can connect to an optical communication device and send and receive optical signals with a communication destination via a transmission path, and an access control unit that grants permission for main signal communication to the subscriber device.

[0011] One aspect of the present invention is an optical communication method executed by an optical communication system that performs optical transmission between subscriber devices and relays optical signals according to their destinations, the optical communication method comprising: a control step of communicating with the subscriber device using control signals; an access control step of granting permission for main signal communication to the subscriber device; an add / drop step of inputting optical signals from the subscriber device and outputting optical signals to the subscriber device; and a multiplexing / demultiplexing step of concentrating optical paths from the subscriber device to another route in the upstream direction and distributing optical paths from the other route to the subscriber device in the downstream direction.

[0012] One aspect of the present invention is an optical communication method executed by an optical communication device that performs optical transmission between subscriber devices and relays optical signals according to their destinations, the optical communication method comprising: a superposition step in which a control device superimposes a control signal for communication with the subscriber device onto a main signal; an access control step in which the control device grants permission for main signal communication to the subscriber device or grants the permission based on instructions from the control device; an add / drop step in which an optical signal is input from the subscriber device and an optical signal is output to the subscriber device; and a multiplexing / demultiplexing step in which optical paths from the subscriber device to another route in the upstream direction are concentrated and optical paths from the other route to the subscriber device in the downstream direction are distributed.

[0013] One aspect of the present invention is an optical communication control method comprising a control step of communicating with a subscriber device using a control signal so that the subscriber device connects to an optical communication device and transmits and receives optical signals to a communication destination via a transmission path, and an access control step of granting permission for main signal communication to the subscriber device. [Effects of the Invention]

[0014] According to the present invention, it is possible to set a route available to a subscriber device depending on the destination, and to relay an optical signal transmitted from the subscriber device depending on the destination. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram illustrating an example of the configuration of an optical communication system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating an example of an optical SW according to an embodiment. [Figure 3] FIG. 2 is a diagram illustrating an example of an optical SW according to an embodiment. [Figure 4] FIG. 2 is a diagram illustrating an example of an optical SW according to an embodiment. [Figure 5] FIG. 2 is a diagram illustrating an example of an optical SW according to an embodiment. [Figure 6] FIG. 2 is a diagram illustrating an example of an optical SW according to an embodiment. [Figure 7] FIG. 10 is a diagram illustrating an example of routing before a wavelength change in an optical SW according to an embodiment. [Figure 8] FIG. 10 is a diagram illustrating an example of routing after a wavelength change in an optical SW according to an embodiment. [Figure 9] FIG. 2 is a diagram illustrating an example of an optical SW according to an embodiment. [Figure 10] FIG. 2 is a diagram illustrating an example of an optical SW according to an embodiment. [Figure 11] FIG. 2 is a diagram illustrating an example of an optical SW according to an embodiment. [Figure 12] FIG. 2 is a diagram illustrating an example of an optical SW according to an embodiment. [Figure 13] FIG. 2 is a diagram illustrating an example of an optical SW according to an embodiment. [Figure 14] FIG. 2 is a diagram illustrating an example of an optical SW according to an embodiment. [Figure 15] FIG. 2 illustrates an example of an access topology according to an embodiment. [Figure 16] FIG. 2 illustrates an example of an access topology according to an embodiment. [Figure 17] FIG. 2 illustrates an example of an access topology according to an embodiment. [Figure 18] FIG. 2 illustrates an example of an access topology according to an embodiment. [Figure 19] FIG. 2 illustrates an example of an access topology according to an embodiment. [Figure 20] FIG. 2 illustrates an example of an access topology according to an embodiment. [Figure 21] FIG. 2 illustrates an example of an access topology according to an embodiment. [Figure 22] FIG. 2 illustrates an example of an access topology according to an embodiment. [Figure 23] FIG. 2 illustrates an example of an access topology according to an embodiment. [Figure 24] FIG. 10 is a diagram illustrating an example where scalability of an optical SW is required according to an embodiment. [Figure 25] FIG. 10 illustrates an example of optical SW scalability according to an embodiment. [Figure 26] FIG. 10 illustrates an example of optical SW scalability according to an embodiment. [Figure 27]1 is a diagram illustrating an example of the configuration of an optical access system according to a first embodiment. [Figure 28] FIG. 10 is a diagram showing an example of a SW connection table according to the embodiment. [Figure 29] FIG. 10 is a diagram showing an example of a user wavelength table according to the same embodiment. [Figure 30] FIG. 10 is a diagram showing an example of an inter-station wavelength table according to the embodiment. [Figure 31] FIG. 2 is a diagram illustrating an example of the configuration of a subscriber device according to the embodiment. [Figure 32] FIG. 2 is a diagram illustrating an example of the configuration of a subscriber device according to the embodiment. [Figure 33] 10 is a flowchart showing an initial setting process of the optical access system according to the embodiment. [Figure 34] FIG. 2 is a diagram illustrating an example of the configuration of an optical access system according to the embodiment. [Figure 35] FIG. 2 is a diagram illustrating a configuration example of an optical access system according to the embodiment. [Figure 36] FIG. 2 is a diagram illustrating an example of the configuration of an optical access system according to the embodiment. [Figure 37] FIG. 2 is a diagram illustrating a configuration example of an optical access system according to the embodiment. [Figure 38] FIG. 10 is a diagram illustrating an example of the configuration of an optical access system according to a second embodiment. [Figure 39] FIG. 2 is a diagram illustrating an example of the configuration of an optical access system according to the embodiment. [Figure 40] FIG. 2 is a diagram illustrating an example of the configuration of an optical access system according to the embodiment. [Figure 41] FIG. 10 is a diagram illustrating an example of the configuration of an optical access system according to a third embodiment. [Figure 42] FIG. 2 is a diagram illustrating an example of the configuration of an optical access system according to the embodiment. [Figure 43] FIG. 2 is a diagram illustrating an example of the configuration of an optical access system according to the embodiment. [Figure 44] FIG. 10 is a diagram showing a configuration example of an optical access system according to the fourth embodiment. [Figure 45]FIG. 2 is a diagram illustrating an example of the configuration of an optical access system according to the embodiment. [Figure 46] FIG. 2 is a diagram illustrating an example of the configuration of an optical access system according to the embodiment. [Figure 47] FIG. 2 is a diagram illustrating an example of the configuration of an optical access system according to the embodiment. [Figure 48] FIG. 10 is a diagram illustrating an example of the configuration of an optical access system according to a fifth embodiment. [Figure 49] FIG. 13 is a diagram illustrating an example of the configuration of an optical access system according to a sixth embodiment. [Figure 50] FIG. 2 is a diagram illustrating an example of the configuration of an optical access system according to the embodiment. [Figure 51] FIG. 13 is a diagram illustrating an example of the configuration of an optical access system according to a seventh embodiment. [Figure 52] FIG. 13 is a diagram illustrating an example of the configuration of an optical access system according to an eighth embodiment. [Figure 53] FIG. 2 is a diagram illustrating an example of the configuration of an optical access system according to the embodiment. [Figure 54] FIG. 2 is a diagram illustrating an example of the configuration of a shutter device according to the embodiment. [Figure 55] FIG. 2 is a diagram illustrating an example of the configuration of a shutter device according to the embodiment. [Figure 56] FIG. 2 is a diagram for explaining the operation of the optical access system according to the embodiment. [Figure 57] FIG. 2 is a diagram illustrating an example of the configuration of an optical access system according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of the present invention will be described in detail below with reference to the drawings. Note that identical parts in multiple drawings are assigned the same reference numerals, and their description will be omitted. In this embodiment, in response to a connection request from each subscriber device, a wavelength controller, an optical switch controller, and a management database managing connection information for all subscribers are used to assign a wavelength to each subscriber device. At this time, a subscriber device control device is used to transmit setting information such as the wavelength to be used to each subscriber device. Communication between this control device and the subscriber devices is performed using, for example, a control signal that is slower than the main signal, which is an optical signal between the subscriber devices, and can be superimposed on the main signal. This enables setting changes and monitoring without affecting the main signal. Furthermore, in this embodiment, an optical switch is controlled to output an optical signal transmitted from a subscriber device to which a wavelength has been assigned to a transmission path corresponding to the forwarding destination on the route to the communication destination. In this embodiment, for example, when a wavelength is used as destination information, the optical switch is controlled to perform routing using the wavelength as destination information. This allows the subscriber device to configure a route available according to the destination, and the optical signal transmitted from the subscriber device is relayed using that route according to the destination. Furthermore, it is possible to reduce delays that occur when transferring packets due to processes for adding or deleting user information and destination information, and due to routing processes.

[0017] The destination information may be a subscriber device, an input port, a combination of a subscriber device and a wavelength, a combination of an input port and a wavelength, or a combination of an input port, a subscriber device, and a wavelength. In the following embodiments, a case where a combination of a subscriber device and a wavelength is used as the destination information will be mainly described.

[0018] FIG. 1 is a diagram illustrating an example of the configuration of an optical communication system 1 according to this embodiment. The optical communication system 1 includes multiple optical switches (SWs) 10. While only two optical SWs 10 are shown in FIG. 1, the number of optical SWs 10 is arbitrary. The optical SWs 10 are connected to a control unit 20. The optical SWs 10 communicate with other optical SWs 10 via an optical communication network 30. The optical communication network 30 may be, for example, a WDM (Wavelength Division Multiplexing) network having various topologies. One or more subscriber devices 40 are connected to the optical SWs 10. The subscriber devices 40 are connected to the optical SWs 10 via an optical access network such as a PON (Passive Optical Network). The subscriber device 40 includes an optical transceiver 41. The optical transceiver 41 is an example of the configuration of an optical transmitter and an optical receiver in a subscriber device. The optical transceiver 41 includes an optical transmitter (Tx) 42 and an optical receiver (Rx) 43. The optical transceiver 41 is a wavelength-tunable optical transmitter / receiver. As the optical transceiver 41, for example, a conventional optical transceiver with an AMCC (Auxiliary Management and Control Channel) function can be used.

[0019] The control unit 20 has an optical transceiver 21. The optical transceiver 21 is an example of the optical transmitting unit and optical receiving unit configuration in the control unit 20. The optical transceiver 21 has an optical transmitter (Tx) 22 and an optical receiver (Rx) 23. The optical transceiver 21 is a tunable wavelength optical transmitter / receiver. The control unit 20 stores a wavelength management table. The wavelength management table is data indicating the wavelengths assigned to each subscriber device 40. The control unit 20 uses the AMCC function to assign wavelengths used by the subscriber device 40 for communication. Below, communication between the subscriber device 40 and the control unit 20 will be exemplified using the AMCC function, but is not limited to this.

[0020] To assign a wavelength to the subscriber device 40 according to its destination, the optical transceiver 41 of the subscriber device 40 and the optical transceiver 21 of the control unit 20 first communicate using AMCC. The control unit 20 refers to a wavelength table and selects a wavelength to assign to the subscriber device 40 according to its destination. As an example, the control unit 20 selects a wavelength from among available wavelengths not used by other paths in a wavelength-multiplexed link on the route. Alternatively, the control unit 20 may assign an individual wavelength to the subscriber device 40. The control unit 20 sets the selected wavelength to the subscriber device 40 using a control signal using AMCC. Then, the control unit 20 switches the optical SW 10 to route the optical signal transmitted from the subscriber device 40 according to its destination. For example, if the wavelength is used as destination information, the control unit 20 switches the optical SW to route to the destination indicated by the wavelength. This connects the opposing subscriber devices 40.

[0021] The optical SW 10 is provided in, for example, an optical gateway (GW). An example of the optical SW 10 provided in the optical GW will be described with reference to FIGS.

[0022] 2 is a diagram illustrating an example of the configuration of the optical SW 10a. The optical SW 10a is connected to a plurality of transmission paths 50, and outputs an optical signal input from one of the transmission paths 50 to the other transmission paths 50. The transmission paths 50 are, for example, optical fibers. The optical SW 10a has ports 11-1-1 to 11-1-P (P is an integer equal to or greater than 2) and ports 11-2-1 to 11-2-Q (Q is an integer equal to or greater than 2). When any one of the ports 11-1-1 to 11-1-P is not specified, or is collectively referred to as port 11-1, and when any one of the ports 11-2-1 to 11-2-Q is not specified, or is collectively referred to as port 11-2. The transmission path 50 connected to port 11-1 is referred to as transmission path 50-1, and the transmission path 50 connected to port 11-2 is referred to as transmission path 50-2.

[0023] Each port 11-1 is connected to a subscriber device 40 via a transmission path 50-1. Each port 11-2 is connected to a subscriber device 40 via a transmission path 50-2. The subscriber device 40 is, for example, an ONU. The transmission path 50-2 may be connected to an optical communication network 30, which is an upper network. In this case, the direction of the subscriber device 40 connected via the transmission path 50-1 is the downstream direction, and the direction of the upper network connected via the transmission path 50-2 is the upstream direction. In addition, the transmission path 50-2 may be provided with other optical communication devices such as an optical SW10.

[0024] Ports 11-1-1, 11-1-2, 11-1-3, ... are connected to subscriber devices 40a-1, 40a-2, 40a-3, ..., which are subscriber devices 40 for destination A, via transmission paths 50-1. Subscriber devices 40a-1, 40a-2, 40a-3, ... are collectively referred to as subscriber device 40a, or when no specific one is specified. One of ports 11-2 (port 11-2-1 in the figure) is connected to a wavelength management control unit 25, which will be described later. Some of ports 11-2-i, 11-2-(i+1), 11-2-(i+2), ... are connected to subscriber devices 40b-1, 40b-2, 40b-3, ..., which are subscriber devices 40 for destination B, via transmission paths 50-2, respectively (i is an integer equal to or greater than 2). The subscriber devices 40b-1, 40b-2, 40b-3, ... are collectively referred to as subscriber device 40b when any one of them is not specified. Ports 11-2-j, 11-2-(j+1), 11-2-(j+2), ... other than port 11-2 connected to the subscriber device 40 of destination B are each connected to subscriber devices 40c-1, 40c-2, 40c-3, ..., which are subscriber devices 40 of destination C, via transmission path 50-2 (j is an integer of 2 or greater). The subscriber devices 40c-1, 40c-2, 40c-3, ... are collectively referred to as subscriber device 40c when any one of them is not specified. The optical SW 10a outputs an optical signal input from port 11-1 to port 11-2, and outputs an optical signal input from port 11-2 to port 11-1. Here, the configuration may be such that other optical communication devices such as optical SW or an optical communication network 30 are interposed between the subscriber device 40 of destination A, the subscriber device 40 of destination B, and the subscriber device 40 of destination C.

[0025] The optical SW 10a is connected to the control unit 20. The control unit 20 has a wavelength management control unit 25 and an optical SW control unit 26. The wavelength management control unit 25 performs wavelength allocation processing by receiving a wavelength allocation request from a subscriber device 40 via an optical signal, assigning a wavelength to the subscriber device 40 that sent the request according to the communication destination, and notifying the subscriber device 40 of the assigned wavelength via an optical signal. For example, the wavelength management control unit 25 may dynamically assign a wavelength to the subscriber device 40 that sent the request according to the communication destination. For optical signals transmitted and received between the wavelength management control unit 25 and the subscriber device 40, it is desirable to use a superposition method of management and control signals that is independent of the communication protocol of the optical signal (main signal) between the subscriber devices 40. For optical signals transmitted and received between the wavelength management control unit 25 and the subscriber device 40, for example, protocol-free AMCC is used.

[0026] While the wavelength assignment process is being executed, the optical SW control unit 26 controls the optical SW 10a to transmit and receive optical signals between the subscriber device 40 and the wavelength management control unit 25. After the wavelength assignment process, the optical SW control unit 26 controls the optical SW 10a to output the optical signal input from the transmission path 50 to the transmission path 50-2 corresponding to the communication destination specified by the combination of the subscriber device 40 that transmitted the input optical signal and the wavelength of the input optical signal.

[0027] Each transmission path 50-2 is provided with a monitoring circuit 60. In the figure, only one monitoring circuit 60 is shown. The monitoring circuit 60 is an example of a monitoring unit. The monitoring circuit 60 has a power splitter 61. The power splitter 61 splits the optical signal transmitted through the transmission path 50-2. The monitoring circuit 60 monitors the optical signal split by the power splitter 61. The monitoring circuit 60 generates monitoring information based on the monitoring results and outputs the generated monitoring information. The monitoring information is information indicating the monitoring results or information obtained from the monitoring results. The monitoring information can be output to, for example, the control unit 20. Furthermore, during communication with other subscriber devices 40, the power splitter 61 can split a control signal transmitted by the subscriber device 40 or superimpose a control signal on a signal between the subscriber devices 40 and transmit it.

[0028] When a subscriber device 40 is connected to the transmission line 50-2, the control unit 20 may be connected to the port 11-1. Alternatively, when a subscriber device 40 is connected to the transmission line 50-2, the subscriber device 40 connected to the transmission line 50-2 may be connected to the control unit 20 via a return transmission line 73. The return transmission line 73 is an optical fiber that inputs an optical signal output from port 11-1-p1 to another port 11-1-p2 (p1 and p2 are integers between 1 and P). In this case, an optical signal transmitted from subscriber device 40b or 40c is input to the optical SW 10a via the transmission line 50-2. The optical SW 10a outputs the optical signal input from the transmission line 50-2 to port 11-1-p1 and inputs the optical signal transmitted through the return transmission line 73 from port 11-1-p2. The optical SW 10a outputs the optical signal input from the port 11-1-p2 from the port 11-2-1 to the control unit 20. In this way, the control unit 20 is connected to the subscriber device 40b or 40c.

[0029] The wavelength management and control unit 25 may perform a wavelength change process to instruct a subscriber device 40 that has performed a wavelength assignment process to change its wavelength. For example, the wavelength management and control unit 25 identifies a subscriber device 40 to be subject to wavelength change based on monitoring information output from the monitoring circuit 60, and performs a wavelength change process on the identified subscriber device 40. The optical SW control unit 26 controls the optical SW 10a during the wavelength change process so that optical signals are transmitted and received between the subscriber device 40 and the wavelength management and control unit 25. After the wavelength change process, when the optical SW control unit 26 receives an optical signal with a changed wavelength from the subscriber device 40, the optical SW control unit 26 controls the optical SW 10a to output the input optical signal to the transmission path 50-2 corresponding to the communication destination. For example, after the wavelength change process, the optical SW control unit 26 receives an optical signal with a changed wavelength from the subscriber device 40 and controls the optical SW 10a to output the input optical signal to the transmission path 50-2 corresponding to the communication destination that used the combination of the source subscriber device 40 and the wavelength before the change. Alternatively, the optical SW control unit 26 may control the optical SW 10a to output an optical signal transmitted from the source subscriber device 40 using the changed wavelength to a transmission path 50-2 different from that used before the wavelength change. In this case, the destination subscriber device 40 is different before and after the wavelength change process. Furthermore, the wavelength management control unit 25 may receive a wavelength change request from the subscriber device 40 during or after communication has ended, and perform wavelength change processing on the requesting subscriber device 40. The wavelength change process may change both the wavelength used by the subscriber device 40 for transmission and the wavelength used for reception, or may change either one of them.

[0030] Fig. 3 is a diagram showing an example of the configuration of an optical SW10b having a return circuit for return communication. In this figure, the same parts as those in the optical SW10a shown in Fig. 2 are given the same reference numerals, and their description will be omitted. Also, in Fig. 3, the control unit 20 is omitted. The optical SW10b is connected to a return transmission line 51. The return transmission line 51 is an optical fiber that inputs an optical signal output from a port 11-2 to another port 11-2. This enables the optical SW10b to perform return communication.

[0031] When the output port of the optical signal is set by the combination of the source subscriber device 40 and the wavelength, the destination may be different for the direction from port 11-1 to port 11-2 to which the return transmission line 51 is connected, and the direction from port 11-2 to which the return transmission line 51 is connected to port 11-1.

[0032] FIG. 4 illustrates an example configuration of an optical SW 10c that performs upstream multicasting. In FIG. 4, the same components as those in the optical SW 10a illustrated in FIG. 2 are denoted by the same reference numerals, and their description will be omitted. Also, the control unit 20 is omitted in FIG. 4. The optical SW 10c includes a distributor 58 that distributes the optical signal output from port 11-2 to multiple components and inputs each of the multiple distributed optical signals to a different port 11-1. The distributor 58 is an example of a first distributor. In FIG. 4, the optical SW 10c inputs the optical signal output from port 11-2 to another port 11-2 via a return transmission line. The optical SW 10c outputs the input optical signal to port 11-1, to which a 1×N power splitter 71 is connected. The optical signal output from port 11-1 is distributed by the power splitter 71 and input to multiple other ports 11-1. The optical SW 10c outputs the optical signals input from these multiple ports 11-1 to different ports 11-2. Note that bidirectional communication is also possible. Downstream optical signals are routed in the opposite direction to the upstream optical signals.

[0033] The optical SW 10c may receive optical signals of multiple wavelengths from port 11-1. In this case, the optical SW 10c distributes the optical signals of multiple wavelengths received from port 11-1 using the distributor 58, and outputs the distributed optical signals to each subscriber device 40 connected to port 11-2 or to a transmission line connected to another terminal. The subscriber device 40 connected to port 11-2 selects and receives an optical signal of a predetermined wavelength from the optical signals of multiple wavelengths. The transmission line connected to another terminal may transmit the optical signals of multiple wavelengths as they are, or may transmit an optical signal of a wavelength selected by a WDM device shown in FIG. 6, which will be described later.

[0034] FIG. 5 illustrates a configuration example of an optical SW 10d that performs downstream multicasting. In FIG. 5, the same components as those in the optical SW 10a illustrated in FIG. 2 are denoted by the same reference numerals, and their description will be omitted. Also, the control unit 20 is omitted in FIG. 5. The optical SW 10d includes a distributor 59 that distributes the optical signal output from port 11-1 to multiple ports and inputs the multiple distributed optical signals to different ports 11-2. The distributor 59 is an example of a second distributor. In FIG. 5, the optical SW 10d inputs the optical signal output from port 11-1 to another port 11-1 via a return transmission line. The optical SW 10d outputs the input optical signal to port 11-2, to which a 1×N power splitter 72 is connected. The optical signal output from port 11-2 is distributed by the power splitter 72 and input to multiple other ports 11-2. The optical SW 10d outputs the optical signals input from the plurality of ports 11-2 to different ports 11-1.

[0035] The optical SW 10d may receive optical signals of multiple wavelengths from port 11-2. In this case, the optical SW 10c divides the optical signals of multiple wavelengths received from port 11-2 using the divider 59 and outputs the divided optical signals to each subscriber device 40 connected to port 11-1. Each subscriber device 40 connected to port 11-1 selects and receives an optical signal of a predetermined wavelength from the received optical signals of multiple wavelengths.

[0036] FIG. 6 is a diagram showing an example of the configuration of an optical SW 10e that performs WDM transmission. In FIG. 6, components identical to those of the optical SW 10a shown in FIG. 2 are assigned the same reference numerals, and their description will be omitted. The optical SW 10e is connected to one or more WDM devices 80. The WDM device 80 is an example of a multiplexing / demultiplexing device. The WDM device 80 multiplexes optical signals of different wavelengths output from multiple ports 11-2 and outputs the multiplexed optical signals to a multiplexed communication transmission path 90. The WDM device 80 also demultiplexes optical signals received via the multiplexed communication transmission path 90 by wavelength and inputs the demultiplexed optical signals to multiplexed communication transmission paths 90. In this way, the WDM device 80 functions as both a multiplexing device that multiplexes optical signals of different wavelengths output from multiple ports 11-2 of the optical SW 10e and outputs the multiplexed optical signals to the multiplexed communication transmission path 90, and a demultiplexing device that demultiplexes optical signals received via the multiplexed communication transmission path 90 by wavelength and inputs the demultiplexed optical signals to different ports 11-2 of the optical SW 10e. The optical SW 10e that performs WDM transmission may have the return transmission line 51 shown in FIG.

[0037] The multiplex communication transmission path 90 is provided with a monitoring circuit 65. The monitoring circuit 65 has a power splitter 66 and WDM devices 67 and 68. The power splitter 66 splits an optical signal transmitted through the multiplex communication transmission path 90. The WDM device 67 demultiplexes the upstream optical signal split by the power splitter 66. The WDM device 68 demultiplexes the downstream optical signal split by the power splitter 66. The monitoring circuit 65 monitors the optical signals demultiplexed by the WDM devices 67 and 68. The monitoring circuit 65 generates monitoring information based on the monitoring results and outputs the generated monitoring information. The monitoring information is information indicating the monitoring results or information obtained from the monitoring results. For example, when the monitoring circuit 65 detects an abnormality in the communication status between subscriber devices 40 by monitoring the optical signal, it outputs monitoring information indicating that the abnormality in the communication status has occurred and information identifying the subscriber device 40 in which the abnormality in the communication status has occurred. The monitoring information can be output to, for example, the control unit 20.

[0038] The monitoring circuit 65 may include a power splitter 69 in each transmission path between the port 11-2 and the WDM device 80. The power splitter 69 splits an optical signal transmitted through the transmission path between the port 11-2 and the WDM device 80, and outputs the split optical signal to the control unit 20.

[0039] The wavelength management and control unit 25 may perform a wavelength change process to instruct a subscriber device 40 that has performed a wavelength allocation process to change its wavelength. For example, the wavelength management and control unit 25 identifies a subscriber device 40 whose wavelength is to be changed based on monitoring information output from the monitoring circuit 65, and performs a wavelength change process on the identified subscriber device 40. The optical SW control unit 26 controls the optical SW 10e during the wavelength change process so that an optical signal is transmitted and received between the subscriber device 40 and the wavelength management and control unit 25. After the wavelength change process, when the optical SW control unit 26 receives an optical signal with a changed wavelength from the subscriber device 40, the optical SW control unit 26 controls the optical SW 10e so that the input optical signal is output from the port 11-2 corresponding to the communication destination. Furthermore, the wavelength management and control unit 25 may receive a wavelength change request from the subscriber device 40 during or after communication has ended, and perform a wavelength change process on the requesting subscriber device 40.

[0040] An example of wavelength change in the optical SW 10e will be described with reference to Figures 7 and 8. Figure 7 is a diagram showing an example of routing before wavelength change in the optical SW 10e. The optical SW 10e is connected to subscriber devices 40, 40a-1, 40a-2, 40a-3, ..., of destination A. The WDM device 80 connected to destination B is described as WDM device 80b, and the WDM device 80 connected to destination C is described as WDM device 80c. The WDM device 80b routes wavelengths λ1 to λ2 between the optical SW 10e and the optical SW 10e. 10 The WDM device 80c transmits and receives an optical signal of wavelength λ 11 ~λ 20 transmits and receives optical signals.

[0041] 7, before the wavelength change, the optical SW 10e outputs an optical signal of wavelength λ1 input from the subscriber device 40a-1 and an optical signal of wavelength λ2 input from the subscriber device 40a-2 from different ports 11-2 to the WDM device 80b. The subscriber device 40a-2 transmits a wavelength change request to the wavelength management and control unit 25 by using a control signal during or after communication has ended. Upon receiving the wavelength change request from the subscriber device 40a-2, the wavelength management and control unit 25 instructs the subscriber device 40a-2 to change the wavelength λ 10 The optical SW control unit 26 performs a wavelength change process to instruct the change to the wavelength λ 1 received from the subscriber device 40a-2. 10 The optical signal of wavelength λ 10 The wavelength management controller 25 controls the optical SW 10e so that the optical signal is output from the port 11-2 corresponding to the optical signal to the WDM device 80b. The wavelength management controller 25 may further change the wavelength used for reception by the subscriber device 40a-2.

[0042] Furthermore, after the wavelength change process, the optical SW control unit 26 may control the optical SW 10e so that the optical signal transmitted from the source subscriber device 40 using the changed wavelength is output to a WDM device 80 different from the WDM device 80 before the wavelength change. Figure 8 is a diagram showing an example of routing after wavelength change in the optical SW 10e when the output destination WDM device 80 is changed. Before the wavelength change, as shown in Figure 7, the subscriber device 40a-1 uses wavelength λ1, and the subscriber device 40a-2 uses wavelength λ2 or wavelength λ 10 During or after the communication, the subscriber device 40a-2 transmits a wavelength change request to the wavelength management control unit 25 by a control signal. Upon receiving the wavelength change request from the subscriber device 40a-2, the wavelength management control unit 25 instructs the subscriber device 40a-2 to use the wavelength λ for communication with the subscriber device 40 at destination C. 11 The optical SW control unit 26 performs a wavelength change process to instruct the change to the wavelength λ 1 received from the subscriber device 40a-2. 11 The optical signal of wavelength λ 11 The optical SW 10e controls the optical switch 10e so that the optical signal is output from the port 11-2 corresponding to the optical signal to the WDM device 80c. The wavelength management controller 25 may further change the wavelength used by the subscriber device 40a-2 for reception.

[0043] If the subscriber device 40a-2 uses wavelength as destination information and does not change the wavelength used for reception, the wavelength management control unit 25 may operate as follows: If wavelength is not used as destination information, the following does not apply.

[0044] (1) The wavelength management control unit 25 releases the transmission wavelength that was used by the subscriber device 40 of destination B, which was the communication destination before the wavelength switching. By releasing the transmission wavelength, the route from the subscriber device 40a-2, which has this wavelength as destination information, to the subscriber device 40 of destination B is reset. After that, the wavelength management control unit 25 reallocates the wavelength that has become vacant due to the release to receive a signal addressed to the subscriber device 40a-2 from the subscriber device 40 of destination C, which is the new communication destination. This is done when the wavelength used for each subscriber device 40 is unique and only vacant wavelengths are allocated.

[0045] (2) When the destination of communication is a subscriber device 40 connected via a different multiplexed communication transmission path 90 before and after the wavelength change of subscriber device 40a-2, the wavelength used before the wavelength change can be reused. However, although the wavelength is used as destination information, for example, if the destination passes through a different transmission path or if the input or output port of an optical switch is different, the same wavelength is treated as a different route. To enable this type of reuse, for example, an "input transmission path," an "output transmission path," or a "combination of all transmission paths constituting the route" can be added to the arguments used as conditions for determining the output destination of the optical signal. For example, the output destination can be determined by the combination of the transmission path or port through which the optical signal is input and the wavelength of the optical signal, or the combination of the transmission path or port through which the optical signal is input, the subscriber device 40 that transmitted the optical signal, and the wavelength of the optical signal.

[0046] In the above, the wavelength change process is explained as being performed when the subscriber device 40 requests a wavelength change, but the wavelength change process is also performed in the same manner based on the monitoring information.

[0047] An optical SW that performs WDM transmission and multicasting will be described using Figures 9 to 12. Figure 9 is a diagram showing an example of the configuration of an optical SW 10f that performs WDM transmission and upstream multicasting. In Figure 9, the optical SW 10f performs upstream multicasting using a single wavelength. As shown in Figure 9, the optical SW 10f has a distribution unit 58 similar to that in Figure 4. In Figure 9, multicasting is performed to terminals B and C. The optical SW 10f outputs an optical signal input from port 11-1 connected to the subscriber device 40 from port 11-2 to which a return transmission line is connected, and inputs an optical signal that has transmitted through the return transmission line from another port 11-2. The optical SW 10f outputs this input optical signal from port 11-1 to which a 1xN power splitter 71 is connected. The optical SW10f receives the optical signals split by the 1×N power splitter 71 from multiple ports 11-1, and outputs one of the input optical signals to port 11-2 connected to terminal B and the other optical signal to port 11-2 connected to terminal C.

[0048] Alternatively, the subscriber device 40 may output a WDM signal. For example, the subscriber device 40 outputs a WDM signal in which an optical signal of wavelength λ1 and an optical signal of wavelength λ2 are multiplexed. Furthermore, the multiple transmission paths between the WDM device 80b and the optical SW10f transmit and receive optical signals of wavelengths λ1, λ2, ... in order from the top. Similarly, the multiple transmission paths between the WDM device 80c and the optical SW10f transmit and receive optical signals of wavelengths λ1, λ2, ... in order from the top.

[0049] The optical SW 10f uses the distributor 58 to distribute the WDM signals of wavelengths λ1 and λ2 input from port 11-1 connected to the subscriber device 40. The optical SW 10f outputs the distributed WDM signal to port 11-2 corresponding to wavelength λ1 among ports 11-2 connected to the WDM device 80b. Furthermore, the optical SW 10f outputs another distributed WDM signal to port 11-2 corresponding to wavelength λ2 among ports 11-2 connected to the WDM device 80c. The WDM device 80b filters the WDM signal input from the port corresponding to wavelength λ1 to block wavelength λ2, and passes the optical signal of wavelength λ1 to output it to the multiplexed communication transmission path 90. The WDM device 80c filters the WDM signal input from the port corresponding to wavelength λ2 to block wavelength λ1, and passes the optical signal of wavelength λ2 to output it to the multiplexed communication transmission path 90.

[0050] FIG. 10 illustrates a case in which the optical switch 10f performs upstream multicasting to multiple destinations using multiple wavelengths. By providing one or more 1×M power splitters 55 on the transmission path 50-1, multiple subscriber devices 40 can be connected to the transmission path 50-1 connected to one port 11-1. In FIG. 10, multiple subscriber devices 40a-1 are connected to one transmission path 50-1, including subscriber devices 40a-1-1, 40a-1-2, and so on. Each of the subscriber devices 40a-1-1, 40a-1-2, and so on uses a different wavelength. Here, the subscriber device 40a-1-1 transmits an optical signal with a wavelength λ1, and the subscriber device 40a-1-2 transmits an optical signal with a wavelength λ2. The optical switch 10f inputs, from port 11-1, an optical signal obtained by multiplexing the optical signal with wavelength λ1 transmitted by the subscriber device 40a-1-1 and the optical signal with wavelength λ2 transmitted by the subscriber device 40a-1-2. The optical SW 10f outputs this input optical signal from port 11-2 to which the return transmission line is connected, and inputs the optical signal that has transmitted through the return transmission line from another port 11-2. The optical SW 10f outputs this input optical signal from port 11-1 to which the 1×N power splitter 71 is connected. The optical SW 10f inputs the optical signals split by the 1×N power splitter 71 from multiple ports 11-1.

[0051] The optical SW10f outputs the optical signal distributed by the power splitter 71 to the port 11-2 corresponding to the wavelength λ1 and the port 11-2 corresponding to the wavelength λ2, among the ports 11-2 connected to the WDM device 80b. Furthermore, the optical SW10f outputs the optical signal distributed by the power splitter 71 to the port 11-2 corresponding to the wavelength λ1 and the port 11-2 corresponding to the wavelength λ2, among the ports 11-2 connected to the WDM device 80c. The WDM device 80b filters the optical signal input from the port corresponding to the wavelength λ1 to pass the optical signal of wavelength λ1 and output it to the multiplexed communication transmission path 90, and filters the optical signal input from the port corresponding to wavelength λ2 to pass the optical signal of wavelength λ2 and output it to the multiplexed communication transmission path 90. Similarly, WDM device 80c filters the optical signal input from the port corresponding to wavelength λ1, passes the optical signal of wavelength λ1, and outputs it to multiplexed communication transmission path 90, and filters the optical signal input from the port corresponding to wavelength λ2, passes the optical signal of wavelength λ2, and outputs it to multiplexed communication transmission path 90.

[0052] Fig. 11 is a diagram showing an example of the configuration of an optical SW 10g that performs WDM transmission and downstream multicast. The optical SW 10g has a distribution unit 59 similar to that in Fig. 5. Furthermore, the optical SW 10f shown in Figs. 9 and 10 and the optical SW 10g shown in Fig. 11 may have a monitoring circuit 65 similar to that in Fig. 6. The wavelength management control unit 25 can perform wavelength change processing in the same manner as described above for a subscriber device 40 in which the monitoring circuit 65 has detected an abnormality in the communication status.

[0053] FIG. 12 illustrates a case in which an optical SW 10g performs WDM transmission and downstream multicasting. The connection configuration illustrated in FIG. 12 differs from the connection configuration illustrated in FIG. 11 in that a WDM device 81 connected to multiple ports 11-1 is provided instead of the WDM device 80 connected to multiple ports 11-2 of the optical SW 10g. One or more subscriber devices 40 are connected to the WDM device 81 on the opposite side of the port 11-1. The optical SW 10g receives a multi-wavelength optical signal from another destination through the port 11-2 and outputs it to the port 11-1 to which the return transmission line of the distribution unit 59 is connected. The multi-wavelength optical signal is directly split by the power splitter 72. The optical SW 10d receives the split multi-wavelength optical signal from the multiple ports 11-2 and outputs the input optical signal to one of the ports 11-1 connected to the WDM device 81. The WDM device 81 filters and passes the optical signal of the wavelength corresponding to the port 11-1 to which the optical signal was input from the optical signal of multiple wavelengths, and outputs the passed optical signal to a transmission path connected to the subscriber device 40.

[0054] Fig. 13 is a diagram showing an example of the configuration of an optical SW 10h that performs electrical processing on an optical signal. In Fig. 13, the same components as those in the optical SW 10b shown in Fig. 3 are assigned the same reference numerals, and their description will be omitted. Also, in Fig. 13, the control unit 20 is omitted. The optical SW 10h differs from the optical SWs 10a to 10g described above in that it further includes ports 12-1 and 12-2. The ports 12-1 and 12-2 are connected to the electrical processing unit 84 via the transmission line 52. Note that the ports connected to the electrical processing unit 84 via the transmission line 52 may also be ports 11-1 and 11-2.

[0055] The optical SW 10h outputs the optical signal input from the subscriber device 40 from port 11-2 or port 12-1 according to the combination of the wavelength and the subscriber device 40 that is the source of the optical signal or the port 11-1 that input the optical signal, under the control of the optical SW control unit 26. Also, the optical SW 10h outputs the optical signal input from port 11-2 from port 11-1 or port 12-1 according to the combination of the wavelength and the port 11-2 that input the optical signal, under the control of the optical SW control unit 26.

[0056] The optical SW 10h outputs an optical signal from port 12-1, thereby dropping the optical signal to the electrical processing unit 84. The electrical processing unit 84 electrically terminates the dropped optical signal, performs various electrical processing such as error correction and concentration, converts the signal into an optical signal, and inputs it to port 12-2 of the optical SW 10h. The optical SW 10h outputs the optical signal input from the electrical processing unit 84 from port 11-1 or 11-2 depending on the destination specified by the combination of port 12-2 and the wavelength. In this manner, the electrical processing unit 84 performs OE (electrical processing addition)-O conversion (O stands for optical, E stands for electrical). Note that the electrical processing unit 84 may simply perform OEO conversion without performing electrical processing for adding functions. During OEO conversion, the electrical processing unit 84 may perform 3R regeneration (re-amplification, re-timing, and re-shaping) or use the threshold effect by inverting the signal from 0 to 1, thereby reducing optical waveform degradation during transmission. The wavelength of the optical signal before conversion into an electrical signal may be the same as or different from the wavelength of the optical signal after conversion from the electrical signal.

[0057] In addition, the port to which the optical SW is output is determined by the combination of the subscriber device transmitting the optical signal and the wavelength, i.e., when the wavelength is used as destination information, the destinations may be different in the direction from port 11-1 to port 11-2 and the direction from port 11-2 to port 11-1, even if the wavelength is the same, in order to pass through the electrical processing unit 84.

[0058] The electrical processing unit 84 includes an O / E (optical / electrical) conversion unit 85, a processing execution unit 86, an E / O (electrical / optical) conversion unit 87, and a storage unit 88. The O / E conversion unit 85 converts an optical signal input from the optical SW 10h into an electrical signal. The processing execution unit 86 includes a processor 861 and an accelerator 862. The processor 861 is, for example, a general-purpose processor such as a central processing unit (CPU). The accelerator 862 is, for example, a processor such as a graphics processing unit (GPU). The processor 861 and the accelerator 862 read and execute programs from the storage unit 88 to perform electrical signal processing on the electrical signal converted by the O / E conversion unit 85. The processing execution unit 86 may perform electrical signal processing for multiple functions. Examples of electrical signal processing include DSP (digital signal processing) for long-distance / high-speed access, mobile fronthaul processing, error correction, etc. The E / O conversion unit 87 converts the electrical signal into an optical signal of a wavelength specified by the optical SW control unit 26 and outputs it to the optical SW 10h. The storage unit 88 stores programs that enable the processor 861 and the accelerator 862 to execute the electrical signal processing functions.

[0059] By using a general-purpose processor as the device architecture for the processing execution unit 86, it is possible to add or change electrical signal processing, and it is also possible to replace it with various functions other than transmission functions. Also, by having the processing execution unit 86 perform DSP for long-distance / high-speed access, it is possible to eliminate the need for a dedicated LSI (Large-Scale Integration) for long-distance / high-speed access, and it is possible to realize flexible functional deployment according to needs.

[0060] The optical SW 10h may be connected to a plurality of electrical processing units 84. In this case, the optical SW 10h has ports 12-1 and 12-2 connected to the respective electrical processing units 84. Each of the electrical processing units 84 may perform different electrical signal processing, or some or all of the electrical processing units 84 may perform the same electrical processing.

[0061] The processing execution unit 86 and the storage unit 88 may be realized using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array).

[0062] FIG. 14 is a diagram showing an example of a connection using an optical SW 10h. Three subscriber devices 40 connected to the optical SW 10h are referred to as subscriber devices 40-1, 40-2, and 40-3. The subscriber devices 40-1, 40-2, and 40-3 are, for example, ONUs. A user 46-1 using the subscriber device 40-1 is a user who performs long-distance or high-speed communications. One or more communication devices of the user 46-1 are connected to the subscriber device 40-1. The subscriber device 40-1 communicates with a destination device via a long-distance line P1. A mobile base station 46-2 is connected to the subscriber device 40-2. In FIG. 14, multiple subscriber devices 40-2 are connected to a single transmission path 50-1 by a power splitter 55. The subscriber device 40-2 communicates with a destination device via a medium-distance line P2. A user 46-3 using the subscriber device 40-3 is a user who performs medium-distance or medium-speed communications. One or more communication devices of user 46-3 communicate with a destination device over medium-distance line P3 via subscriber device 40-3. Optical signals from long-distance line P1, medium-distance line P2, and medium-distance line P3 are wavelength-multiplexed and transmitted over multiplexed communication transmission path 90 connected to a core NW (network). Electrical processing unit 84 has a DSP function for long-distance / high-speed access, a mobile fronthaul processing function, an error correction function, etc.

[0063] The operation of the optical SW 10h will be described using Figures 13 and 14. The optical SW 10h outputs an upstream optical signal transmitted by the subscriber device 40-1 to the electrical processing unit 84. The O / E conversion unit 85 of the electrical processing unit 84 converts the input optical signal into an electrical signal. The processing execution unit 86 performs DSP processing on the converted electrical signal for long-distance / high-speed access. The E / O conversion unit 87 converts the DSP-processed electrical signal into an optical signal and outputs it to the optical SW 10h. The wavelength after conversion may be the same as or different from the wavelength when input to the electrical processing unit 84. The optical SW 10h outputs the optical signal input from the electrical processing unit 84 to the multiplexed communication transmission path 90 from port 11-2.

[0064] The optical SW 10h also receives a downstream optical signal transmitted through the multiplexed communication transmission path 90 and addressed to the subscriber device 40-1. The optical SW 10h outputs the received downstream optical signal from port 12-1 to the electrical processing unit 84 in accordance with the combination of the input port 51-2 and the wavelength. The O / E conversion unit 85 of the electrical processing unit 84 converts the received optical signal into an electrical signal, and the processing execution unit 86 performs DSP processing on the converted electrical signal for long-distance / high-speed access. The E / O conversion unit 87 converts the DSP-processed electrical signal into an optical signal and outputs the optical signal to the optical SW 10h. The wavelength of the optical signal after conversion may be the same as or different from the wavelength when input to the electrical processing unit 84. The optical SW 10h outputs the optical signal received from the electrical processing unit 84 to port 11-1, which is connected to the subscriber device 40-1.

[0065] The optical signals transmitted and received by the subscriber device 40-2 are also processed in the same manner as the optical signals transmitted and received by the subscriber device 40-1. However, the processing execution unit 86 performs mobile fronthaul processing on the optical signals transmitted and received by the subscriber device 40-2. The processing execution unit 86 determines the signal processing to be performed on the electrical signals based on any information included in the electrical signals.

[0066] On the other hand, the optical SW 10h outputs an upstream optical signal input from the subscriber device 40-3 from port 11-2 to the multiplexed communication transmission path 90. The optical SW 10h also inputs a downstream optical signal destined for the subscriber device 40-3 that has propagated through the multiplexed communication transmission path 90, and outputs the downstream optical signal to port 11-1 connected to the subscriber device 40-3 in accordance with the combination of the port 11-2 into which the optical signal was input and the wavelength.

[0067] Next, the access topology to the optical SW will be explained using FIGS.

[0068] FIG. 15 is a diagram showing a PDS (Passive Double Star) type access topology using time division multiplexing. The optical SW 1001 can be any of the optical SWs 10a to 10h described above. The optical SW 1001 has ports 11-1-1 to 11-1-P and ports 11-2-1 to 11-2-Q. The transmission path 50-1 connected to port 11-1-p (p is an integer between 1 and P) will also be referred to as transmission path 50-1-p, and the transmission path 50-2 connected to port 11-2-q (q is an integer between 1 and Q) will also be referred to as transmission path 50-2-q. In FIG. 15, port 11-2-q is connected to ground #q via transmission path 50-2-q.

[0069] A power splitter 56 is provided on the transmission path 50-1-p. Np (Np is an integer equal to or greater than 2) subscriber devices 40-p are connected to the power splitter 56 in a star configuration. The Np subscriber devices 40-p are referred to as subscriber devices 40-p-1 to 40-p-Np, and the transmission path 50-1-p between the subscriber device 40-p-np (np is an integer equal to or greater than 1 and equal to or less than Np) and the power splitter 56 is referred to as 50-1-p-np. The subscriber devices 40-p-1 to 40-p-Np use the same wavelength through time division multiplexing. The wavelength used for the upstream optical signal is different from the wavelength used for the downstream optical signal.

[0070] The optical SW1001 receives time-division multiplexed downstream optical signals of wavelength λ1 destined for each of the subscriber devices 40-p-1 to 40-p-Np from port 11-2-q. The optical SW1001 outputs the received downstream optical signals from port 11-1-p, which is the output destination corresponding to the combination of port 11-2-q and wavelength λ1. The power splitter 56 receives time-division multiplexed downstream optical signals from the transmission path 50-1-p, splits the input optical signals, and outputs them to the transmission paths 50-1-p-1 to 50-1-p-Np. The subscriber devices 40-p-1 to 40-p-Np receive the time-division multiplexed optical signals and select the downstream optical signals destined for their own devices from the received optical signals.

[0071] Furthermore, the subscriber devices 40-p-1 to 40-p-Np transmit upstream optical signals of the same wavelength λ2 that have been time-division multiplexed using TDMA (time division multiplexing access). The power splitter 56 receives the upstream optical signals of wavelength λ2 from each of the transmission paths 50-1-p-1 to 50-1-p-Np, time-division multiplexes the received optical signals, and outputs them to the transmission path 50-1-p. The optical SW 1001 outputs the time-division multiplexed upstream optical signals from port 11-2-q that corresponds to the combination of port 11-1-p and wavelength λ2.

[0072] It should be noted that a PDS type access topology can be applied to any one or more of the transmission paths 50-1-1 to 50-1-P.

[0073] FIG. 16 is a diagram showing a PDS-type access topology using wavelength multiplexing. The optical SW 1002 can be any of the optical SWs 10a to 10h described above. The optical SW 1002 is connected to one or more WDM devices 81. The WDM device 81 multiplexes downstream optical signals of different wavelengths output from multiple ports 11-1 and outputs the multiplexed optical signals to a multiplexed communication transmission path 91. The WDM device 81 also demultiplexes upstream wavelength-multiplexed optical signals received via the multiplexed communication transmission path 91 and inputs the demultiplexed optical signals to different ports 11-1. A power splitter 56 is provided in the multiplexed communication transmission path 91. N (N is an integer equal to or greater than 2) subscriber devices 40 are connected to the power splitter 56 in a star configuration. The subscriber devices 40 and the power splitter 56 are connected by a transmission path 92. The multiple subscriber devices 40 connected to the power splitter 56 each transmit and receive optical signals of different wavelengths.

[0074] 16, ports 11-1-p to 11-1-(p+N) of the optical SW1002 are connected to the WDM device 81 via a transmission line 50-1 (p and N are integers equal to or greater than 1, and p+N is an integer equal to or less than P). Also, the power splitter 56 is connected to the subscriber devices 40-p to 40-(p+N).

[0075] Optical SW1002 outputs wavelength λ from port 11-2-(q+n). 1(q+n) 16 shows an example where q=1. The optical SW 1002 receives a downstream optical signal of wavelength λ 1 input from port 11-2-(q+n) and sends it to the subscriber device 40-(p+n). 1(1+n) The downstream optical signal is sent to port 11-2-(q+n) with wavelength λ 1(1+n) The optical switch 1002 routes the wavelength λ 1 input from the port 11-2-1 to the output port 11-1-(p+n) according to the combination of the wavelength λ 1 input from the port 11-2-1. 11 The downstream optical signal of wavelength λ is routed to port 11-1-p, and the downstream optical signal of wavelength λ is input from port 11-2-2. 12 The downstream optical signal is routed to port 11-1-(p+1).

[0076] The WDM device 81 divides the wavelengths λ 1 output from the ports 11-1-p to 11-1-(p+N) into 11 ~λ 1N The power splitter 56 multiplexes the wavelength-multiplexed downstream optical signals and outputs them to a multiplexed communication transmission path 91. The power splitter 56 receives the wavelength-multiplexed downstream optical signals from the multiplexed communication transmission path 91, splits the input downstream optical signals as they are, and outputs them to transmission paths 92 between the subscriber devices 40-p to 40-(p+N). The subscriber devices 40-p to 40-(p+N) receive the wavelength-multiplexed downstream optical signals and select, from the received optical signals, downstream optical signals of the wavelengths used by the respective devices.

[0077] In addition, the subscriber unit 40-(p+n) receives a signal of wavelength λ 2(1+n) The power splitter 56 receives the upstream optical signals from the subscriber units 40-p to 40-(p+N) via the transmission line 92, and transmits the received upstream optical signals of wavelength λ 21 ~λ 2(1+N) The WDM device 81 wavelength-multiplexes the upstream optical signals and outputs them to the multiplexed communication transmission line 91. The WDM device 81 receives the wavelength-multiplexed upstream optical signals from the multiplexed communication transmission line 91 and separates them into wavelengths. 2(1+n) The upstream optical signals are input to the ports 11-1-(p+n), respectively. 2(1+n) The upstream optical signal is input to port 11-1-(p+n) with wavelength λ 2(1+n) The signal is output from the output port 11-2-(q+n) corresponding to the combination of the wavelength λ 21 The upstream optical signal of wavelength λ 1 is input from port 11-1-p and output from port 11-2-1. 22 The upstream optical signal is input from port 11-1-(p+1) and output from port 11-2-2. Note that a WDM device may be placed after the optical SW, as shown in FIG.

[0078] 17 is a diagram showing a PDS-type access topology that uses wavelength multiplexing and has a WDM device placed after the optical SW. The optical SWs 10a to 10h described above can be used as the optical SW 1003. A port 11-2-q (q is an integer between 1 and Q) of the optical SW 1003 is connected to the WDM device 97 via a transmission line 50-2-q. The WDM device 97 is connected to a ground #n (n is an integer between 1 and N) via a transmission line 50-2-qn. A power splitter 56 is provided in the transmission line 50-1-p connected to the port 11-1-p of the optical SW 1003. N subscriber devices 40-p-1 to 40-pN are connected to the power splitter 56 in a star configuration.

[0079] The WDM device 97 receives the wavelength λ 1n The WDM device 97 receives the downstream optical signals λ 1 - λ n , which are destined for the subscriber device 40-pn, from the transmission line 50-2-qn. 11 ~λ 1N A wavelength-multiplexed signal obtained by multiplexing downstream optical signals of the above signals is input to the optical SW 1003. The optical SW 1003 outputs the downstream wavelength-multiplexed signal input from port 11-2-q from the output destination port 11-1-p. The power splitter 56 splits the wavelength-multiplexed signal input from the transmission path 50-1-p and outputs it to the transmission paths 50-1-p-1 to 50-1-pN. The subscriber devices 40-p-1 to 40-pN receive the wavelength-multiplexed signal and select downstream optical signals addressed to the subscriber device itself from the received optical signals. As a result, the subscriber device 40-pn receives downstream optical signals of wavelength λ from the ground #n. 1n The optical signal is received.

[0080] The subscriber unit 40-pn also receives a signal of wavelength λ 2n The power splitter 56 transmits an upstream optical signal of wavelength λ from each of the subscriber units 40-p-1 to 40-pN via the transmission lines 50-1-p-1 to 50-1-pN. 21 ~λ 2N The power splitter 56 receives an upstream optical signal of wavelength λ 21 ~λ 2NThe optical SW 1003 outputs a wavelength multiplexed signal obtained by wavelength-multiplexing the upstream optical signals of wavelength λ to the transmission line 50-1-p. 21 ~λ 2N The optical SW 1003 outputs the upstream wavelength-multiplexed signal from the output port 11-2-q to the transmission line 50-2-q. The WDM device 97 receives the wavelength-multiplexed upstream optical signal from the transmission line 50-2-q and wavelength-separates it. The WDM device 97 separates the wavelengths of the upstream optical signals of wavelength λ 2n The upstream optical signal of wavelength λ 1 transmitted by the subscriber device 40-pn is output to the transmission line 50-2-n connected to the ground #n. 2n The optical signal is transmitted to ground #n.

[0081] Fig. 18 is a diagram showing a bus-type access topology using time division multiplexing. The optical SW 1004 can be any of the optical SWs 10a to 10h described above. The access topology shown in Fig. 18 differs from the access topology shown in Fig. 15 in that a plurality of subscriber devices 40-p-1 to 40-p-Np are connected to a transmission line 50-1-p in a bus configuration. One or more power splitters 55 are provided on the transmission line 50-1-p. A power splitter 55 to which a subscriber device 40-pn (n is an integer between 1 and Np-1) is connected is referred to as a power splitter 55-n.

[0082] The subscriber devices 40-p-1 to 40-p-Np use the same wavelengths through time division multiplexing. The wavelengths used for the upstream optical signals are different from those used for the downstream optical signals. The transmission path 50-2-1 connected to the terminal #1 transmits downstream optical signals with a time division multiplexed wavelength λ1 addressed to each of the subscriber devices 40-p-1 to 40-p-Np. The optical SW 1004 inputs the downstream optical signals with a time division multiplexed wavelength λ1 transmitted through the transmission path 50-2-1 from port 11-2-1. The optical SW 1004 routes the input downstream optical signals to the destination port 11-1-p according to the combination of port 11-2-1 (or terminal #1) and wavelength λ1. The optical SW 1004 outputs the downstream optical signals with a time division multiplexed wavelength λ1 from port 11-1-p to the transmission path 50-1-p. The power splitter 55-n branches the time-division multiplexed downstream optical signal from the transmission path 50-1-p and outputs the branched downstream optical signal to the subscriber device 40-pn. The subscriber devices 40-p-1 to 40-p-Np receive the time-division multiplexed downstream optical signals and select the downstream optical signal addressed to the subscriber device from the received downstream optical signals.

[0083] Furthermore, the subscriber devices 40-p-1 to 40-p-Np transmit upstream optical signals of the same wavelength λ2 that have been time-division multiplexed using TDMA (Time Division Multiple Access). Each power splitter 55-n time-division multiplexes the upstream optical signal of wavelength λ2 input from the subscriber device 40-pn onto the upstream optical signal transmitting through the transmission path 50-1-p. The optical SW 1004 inputs the time-division multiplexed upstream optical signal from port 11-1-p, routes it to destination port 11-2-1 according to the combination of port 11-1-p and wavelength λ2, and outputs it to the transmission path 50-2-1 connected to terminal #1.

[0084] A bus-type access topology can be applied to any one or more of the transmission paths 50-1-1 to 50-1-P.

[0085] FIG. 19 is a diagram showing a bus-type access topology using wavelength multiplexing. The optical SW 1005 can be any of the optical SWs 10a to 10h described above. The access topology shown in FIG. 19 differs from the access topology shown in FIG. 16 in that a plurality of subscriber devices 40-p to 40-(p+N) are connected to a multiplexed communication transmission line 91 in a bus configuration. The subscriber devices 40-p to 40-(p+N) transmit and receive optical signals of different wavelengths. The multiplexed communication transmission line 91 is provided with one or more power splitters 55. A power splitter 55 connected to a subscriber device 40-(p+n) (n is an integer between 0 and N-1, and N is an integer greater than or equal to 1) is referred to as a power splitter 55-(p+n).

[0086] The optical SW 1005 outputs a wavelength λ from port 11-2-(q+n) in the same manner as the optical SW 1002 shown in FIG. 1(1+n) 19 shows an example where q=1. The optical SW 1005 receives a downstream optical signal of wavelength λ 1 input from port 11-2-(q+n) and sends it to the subscriber device 40-(p+n). 1(1+n) The downstream optical signal is sent to port 11-2-(q+n) with wavelength λ 1(1+n) The packet is routed to the output port 11-1-(p+n) according to the combination of the above.

[0087] The WDM device 81 divides the wavelengths λ 1 output from the ports 11-1-p to 11-1-(p+N) into 11 ~λ 1N The downstream optical signals are multiplexed and output to the multiplexed communication transmission path 91. The power splitter 55-(p+n) branches the wavelength-multiplexed downstream optical signals from the multiplexed communication transmission path 91 and outputs the branched downstream optical signals to the subscriber devices 40-(p+n). The subscriber devices 40-p to 40-(p+N) receive the wavelength-multiplexed downstream optical signals and select the downstream optical signal addressed to the subscriber device from the received downstream optical signals.

[0088] In addition, the subscriber unit 40-(p+n) has a wavelength λ 2(1+n)Each power splitter 55-(p+n) transmits an upstream optical signal of wavelength λ 1 transmitted through the multiplexed communication transmission line 91. 2(2+n) ~λ 2N The optical signal of wavelength λ input from the subscriber unit 40-(p+n) 2(1+n) The WDM device 81 receives the wavelength-multiplexed upstream optical signal from the multiplexed communication transmission line 91 and multiplexes the upstream optical signal of wavelength λ 21 ~λ 2N The WDM device 81 separates the upstream optical signals into the upstream optical signals of wavelength λ 2(1+n) The optical SW 1005 inputs the upstream optical signal of wavelength λ to the port 11-1-(p+n) in the same manner as the optical SW 1002 shown in FIG. 2(1+n) The upstream optical signal is input to port 11-1-(p+n) with wavelength λ 2(1+n) The signal is output from the output port 11-2-(q+n) corresponding to the combination of the wavelength λ 21 The upstream optical signal of wavelength λ 1 is input from port 11-1-p and output from port 11-2-1. 22 The upstream optical signal is input from port 11-1-(p+1) and output from port 11-2-2. Note that a WDM device may be placed after the optical SW, as shown in FIG.

[0089] FIG. 20 is a diagram showing a bus-type access topology using wavelength multiplexing and in which a WDM device is placed after an optical SW. The optical SWs 10a to 10h described above can be used as the optical SW 1006. In FIG. 20, the same components as those in FIG. 17 are denoted by the same reference numerals. A port 11-2-q (q is an integer between 1 and Q) of the optical SW 1006 is connected to the WDM device 97 via a transmission line 50-2-q. The WDM device 97 is connected to a ground #n (n is an integer between 1 and N, N is an integer between 2 and 3) via a transmission line 50-2-qn. One or more power splitters 55 are provided in the transmission line 50-1-p connected to a port 11-1-p (p is an integer between 1 and P) of the optical SW 1006. The power splitter 55 connected to a subscriber device 40-pn is referred to as a power splitter 55-n.

[0090] The WDM device 97 receives the wavelength λ 1n The WDM device 97 receives the downstream optical signals of wavelengths λ 1 to λ n from the transmission lines 50-2-qn. 11 ~λ 1N The wavelength-multiplexed signal obtained by multiplexing the downstream optical signals of the above mentioned signals is input to the optical SW 1006. The optical SW 1006 outputs the downstream wavelength-multiplexed signal input from port 11-2-q from the output port 11-1-p. The power splitter 55-n branches the downstream wavelength-multiplexed signal from the transmission line 50-1-p and outputs the branched downstream wavelength-multiplexed signal to the subscriber device 40-pn. The subscriber devices 40-p-1 to 40-pN select the downstream optical signal addressed to the subscriber device itself from the received downstream wavelength-multiplexed signal. As a result, the subscriber device 40-pn receives the downstream optical signal of wavelength λ from the ground #n. 1n The optical signal is received.

[0091] The subscriber unit 40-pn also receives a signal of wavelength λ 2n Each power splitter 55-n splits the wavelength λ input from the subscriber unit 40-pn into an upstream optical signal transmitted through the transmission line 50-1-p. 2n The optical SW1006 wavelength-multiplexes the upstream optical signal of wavelength λ 21 ~λ 2N The optical SW 1006 outputs the upstream wavelength-multiplexed signal from the output port 11-2-q to the transmission line 50-2-q. The WDM device 97 receives the wavelength-multiplexed signal from the transmission line 50-2-q and demultiplexes it. The WDM device 97 demultiplexes the wavelengths of the upstream optical signals of wavelength λ 2n The upstream optical signal of wavelength λ 1 transmitted by the subscriber device 40-pn is output to the transmission line 50-2-qn connected to the ground #n. 2n The optical signal is transmitted to ground #n.

[0092] FIG. 21 is a diagram showing a loop-type access topology. As the optical SW1007, the above-described optical SW10a to 10h can be used. Some ports 11-1-p1 to 11-1-pN (p1 < pN, p1 is an integer of 1 or more, pN is an integer of P or less) of the optical SW1007 are connected to a WDM access ring network 31 that transmits optical signals of multiple wavelengths. Optical signals of some wavelengths used in the WDM access ring network 31 are transmitted to the communication destination subscriber device 40 or the upper NW via the optical SW1007. In the topology shown in FIG. 21, without using a WDM multiplexer / demultiplexer, communication is performed by connecting the opposing subscriber devices 40 with two transmission paths.

[0093] The WDM access ring network 31 is a network in which R Add / Drop nodes 32 are connected by a transmission path 53. FIG. 21 shows an example where R = 4. The R Add / Drop nodes 32 are described as Add / Drop nodes 32-1 to 32-R, and the transmission path 53 between the Add / Drop node 32-r (r is an integer of 1 or more and R or less) and the Add / Drop node 32-(r + 1) is described as the transmission path 53-r. However, the Add / Drop node 32-(R + 1) is regarded as the Add / Drop node 32-1. The Add / Drop node 32-1 is connected to the port 11-1-pn (pn is an integer of p1 or more and pN or less) of the optical SW1007 via the transmission path 50-1-pn.

[0094] The add / drop node 32 includes a demultiplexing unit 33, an optical SW 34, and a multiplexing unit 35. The demultiplexing unit 33 of the add / drop node 32-r (r is an integer between 2 and R) demultiplexes a wavelength-multiplexed optical signal input from the transmission path 53-(r-1) and outputs the optical signal obtained by demultiplexing to the optical SW 34. The optical SW 34 is connected to one or more subscriber devices 40. In the figure, only one subscriber device 40 connected to the optical SW 34 is shown. The optical SW 34 drops an optical signal of a wavelength corresponding to the node itself from the optical signals input from the demultiplexing unit 33. The optical receiver 43 of the subscriber device 40 receives the optical signal dropped by the optical SW 34. The optical SW 34 also inputs an optical signal transmitted by the optical transmitter 42 of the subscriber device 40 and outputs the input optical signal and the optical signal that was not dropped to the multiplexing unit 35. The multiplexing unit 35 of the add / drop node 32-r multiplexes the optical signals input from the optical SW 34 and outputs the multiplexed signal to the transmission path 53-r. The optical SW 34 of the add / drop node 32-1 drops the optical signals of the wavelength corresponding to its own node from the optical signals demultiplexed by the demultiplexing unit 33, and inputs the optical signals of each wavelength to the transmission path 50-1-pn1 (pn1=1, 3, 5, ..., p(N-1)). The port 11-1-pn1 of the optical SW 1007 inputs the optical signals dropped by the add / drop node 32-1 from the transmission path 50-1-pn1. In addition, the optical SW34 of the Add / Drop node 32-1 inputs the optical signal output by the optical SW1007 from port 11-1-pn2 (pn2 = 2, 4, 6, ..., pN) from the transmission path 50-1-pn2, and outputs the input optical signal and the optical signal that was not dropped to the multiplexer 35.

[0095] As a result, ONU#1, which is a subscriber device 40 connected to the Add / Drop node 32-4 of the WDM access ring network 31, and ONU#2, which is a subscriber device 40 connected to ports 11-2-1 and 11-2-2 of the optical SW1007, communicate as follows.

[0096] ONU#1 transmits an optical signal of wavelength λ1 to add / drop node 32-4. The multiplexing unit 35 of add / drop node 32-4 multiplexes the optical signal of wavelength λ1 input by optical SW34 with the optical signal that was not dropped by optical SW34, and outputs the multiplexed signal to add / drop node 32-1. The optical SW34 of add / drop node 32-1 drops the optical signal of wavelength λ1 demultiplexed by demultiplexing unit 33, and outputs the optical signal that was not dropped to the multiplexing unit 35. Port 11-1-p1 of optical SW1007 inputs the optical signal of wavelength λ1 dropped by add / drop node 32-1 from transmission path 50-1-p1. Optical SW1007 outputs the optical signal of wavelength λ1 input from port 11-1-p1 from port 11-2-1. The optical receiver 43 of ONU#2 receives the optical signal of wavelength λ1 transmitted through transmission path 50-2-1.

[0097] The optical transmitter 42 of ONU#2 transmits a downstream optical signal of wavelength λ2. Port 11-2-2 of optical SW1007 receives the optical signal transmitted by ONU#2 via transmission path 50-2-2. The optical SW1007 outputs the downstream optical signal of wavelength λ2 received via port 11-2-2 from port 11-1-p2. The optical SW34 of add / drop node 32-1 receives the optical signal of wavelength λ2 output by optical SW1007 via transmission path 50-1-p2, and outputs the received optical signal and the optical signal that was not dropped to the multiplexer 35. The optical signal of wavelength λ2 is input to add / drop node 32-4 via add / drop nodes 32-2 and 32-3. The optical SW34 of add / drop node 32-4 drops the optical signal of wavelength λ2. The optical receiver 43 of the ONU#1 receives the optical signal with wavelength λ2 dropped by the add / drop node 32-4.

[0098] Fig. 22 is a diagram showing a loop-type access topology using a WDM multiplexer / demultiplexer. The optical SWs 10a to 10h described above can be used as the optical SW 1008. The access topology shown in Fig. 22 differs from the access topology shown in Fig. 21 in that the optical SW 1008 and the WDM access ring network 31 are connected via WDM device 81 and WDM device 89.

[0099] The Add / Drop node 32-1 of the WDM access ring network 31 and the WDM device 89 are connected by transmission lines 93-1 to 93-N (N is an integer equal to or greater than 2). The WDM device 89 receives wavelengths λ 1 from the transmission lines 93-n1 (n1=1, 3, 5, ..., N-1). n1 and outputs a multiplexed signal obtained by multiplexing the received upstream optical signals to the multiplex communication transmission line 91. The WDM device 89 also demultiplexes the downstream wavelength-multiplexed optical signal received via the multiplex communication transmission line 91, and outputs the demultiplexed wavelengths λ n2 The downstream optical signal is input to a transmission line 93-n2 (n2=2, 4, 6, . . . , N).

[0100] The WDM device 81 demultiplexes the upstream wavelength-multiplexed optical signal received via the multiplexed communication transmission line 91, and divides the demultiplexed wavelengths λ n1 The WDM device 81 inputs the upstream optical signals of wavelengths λ 1 and λ 2 output from the ports 11-1-pn1 and 11-1-pn2, respectively. n2 The downstream optical signals are received, and the received downstream signals are multiplexed and output to the multiplex communication transmission line 91.

[0101] As a result, ONU#1, which is a subscriber device 40 connected to the Add / Drop node 32-4 of the WDM access ring network 31, and ONU#2, which is a subscriber device 40 connected to ports 11-2-1 and 11-2-2 of the optical SW 1008, communicate as follows. Note that the case where N=18 will be described as an example.

[0102] ONU#1 transmits an upstream optical signal of wavelength λ1 to add / drop node 32-4. In addition, other ONUs transmit upstream optical signals of wavelengths λ3 and λ5 to add / drop node 32-4. The optical SW34 of add / drop node 32-4 inputs the optical signals of wavelengths λ1, λ3, and λ5. The multiplexing unit 35 of add / drop node 32-4 multiplexes the optical signals of wavelengths λ1, λ3, and λ5 input by optical SW34 with the optical signals that were not dropped by optical SW34, and outputs the multiplexed signal to add / drop node 32-1. The optical SW34 of add / drop node 32-1 multiplexes the optical signals of wavelengths λ1, λ3, λ5, ...λ demultiplexed by demultiplexing unit 33. 17 , λ1, λ3, λ5, . . . , λ6 input from the transmission lines 93-1, 93-3, 93-5, . . . , 93-17, respectively. 17 The multiplexed signal obtained by multiplexing the upstream optical signals is output to the multiplexed communication transmission line 91.

[0103] The WDM device 81 receives wavelength-multiplexed upstream optical signals from the multiplexed communication transmission line 91 and separates the wavelengths. 17 The upstream optical signals of wavelength λ1 are input to ports 11-1-p1, 11-1-p3, 11-1-p5, ..., 11-1-p17 of the optical SW 1008. The optical SW 1008 outputs the upstream optical signal of wavelength λ1 from the output port 11-2-1. The optical receiver 43 of ONU #2 receives the optical signal of wavelength λ1 transmitted through the transmission path 50-2-1.

[0104] The optical transmitter 42 of ONU#2 transmits a downstream optical signal with wavelength λ2. The port 11-2-2 of the optical SW 1008 receives the optical signal transmitted by ONU#2 from the transmission path 50-2-2. The optical SW 1008 outputs the downstream optical signal with wavelength λ2 received from port 11-2-2 from port 11-1-p2. Furthermore, the optical SW 1008 receives the downstream optical signal with wavelength λ4, λ6, ..., λ received from ports 11-2-4, 11-2-6, ..., 11-2-18, respectively. 18 The downstream optical signals are output from ports 11-1-p4, 11-2-p6, . . . , 11-2-p18.

[0105] The WDM device 81 divides the wavelengths λ2, λ4, λ6, . . . , λ18 output from the ports 11-1-p2, 11-1-p4, 11-1-p6, . . . , 11-1-p18, respectively. 18 The wavelength-multiplexed signal obtained by multiplexing the downstream optical signals is output to the multiplexed communication transmission line 91. The WDM device 89 demultiplexes the wavelength-multiplexed signal transmitted through the multiplexed communication transmission line 91, and outputs the wavelengths λ2, λ4, λ6, ..., λ 18 , λ2, λ4, λ6, . . . , λ18 respectively. The optical SW 34 of the Add / Drop node 32-1 outputs the downstream optical signals of wavelengths λ2, λ4, λ6, . . . , λ18 output from the WDM device 89. 18 These optical signals are input from the transmission paths 93-2, 93-4, 93-6, ..., 93-18, and the input optical signals and the optical signals that were not dropped are output to the multiplexing unit 35. The multiplexing unit 35 multiplexes the optical signals input from the optical SW 34, and outputs the multiplexed signals to the transmission path 53-1.

[0106] The demultiplexing unit 33 of the add / drop node 32-2 demultiplexes the optical signal input from the transmission line 53-1 and outputs the demultiplexed signal to the optical SW 34. The optical SW 34 demultiplexes the optical signal of wavelength λ corresponding to the node itself. 14 , λ 16 , λ 18 The optical signal of wavelength λ is dropped. 14 , λ 16 , λ 18 The optical signals of wavelengths λ 1 transmitted by the optical transmitters 42 of the respective subscriber devices 40 are transmitted to the optical receivers 43 of the respective subscriber devices 40. 13 , λ 15 , λ 17 The optical SW 34 receives the optical signal from the optical SW 34 and outputs the received optical signal and the optical signal that was not dropped to the multiplexer 35. The multiplexer 35 multiplexes the optical signals received from the optical SW 34 and outputs the multiplexed signal to the transmission line 53-2.

[0107] The add / drop node 32-3 operates in the same manner as the add / drop node 32-2, except that the optical SW 34 of the add / drop node 32-3 outputs the wavelengths λ8 and λ1 corresponding to the node itself. 10 , λ 12The optical signal of wavelengths λ7, λ9, and λ 11 The add / drop node 32-4 receives an optical signal of wavelength λ2. The demultiplexing unit 33 of the add / drop node 32-4 demultiplexes the wavelength-multiplexed optical signal received from the transmission path 53-3 and outputs the demultiplexed signal to the optical SW 34. The optical SW 34 of the add / drop node 32-4 drops the optical signals of wavelengths λ2, λ4, and λ6 corresponding to the node itself. The optical receiver 43 of the ONU #1 receives the optical signal of wavelength λ2 dropped by the optical SW 34 of the add / drop node 32-4.

[0108] FIG. 23 is a diagram showing an access topology in which one loop is formed at two access planes. The optical SWs 10a to 10h described above can be used as the optical SW 1009a and the optical SW 1009b. The optical SW 1009a and the optical SW 1009b are collectively referred to as the optical SW 1009. The two ports 11-1 of the optical SW 1009 are connected to both ends of a single transmission line 54. One or more power splitters 57 are connected to the transmission line 54. The power splitter 57 is connected to the optical transmitters 42 of one or more subscriber devices 40 via a multiplexer 82 and an optical SW 95, and to the optical receivers 43 of one or more subscriber devices 40 via a demultiplexer 83 and an optical SW 96. Each subscriber device 40 transmits and receives optical signals of different wavelengths.

[0109] The transmission line 54 connected to the optical SW 1009a is referred to as the transmission line 54a, the two ports 11-1 connected to the transmission line 54a are referred to as ports 11a-1-p1 and 11a-1-p2, the transmission line 54 connected to the optical SW 1009b is referred to as the transmission line 54b, and the two ports 11-1 connected to the transmission line 54b are referred to as ports 11b-1-p1 and 11b-1-p2. The N (N is an integer of 1 or more) power splitters 57 connected to the transmission line 54a are referred to as power splitters 57a-1 to 57a-N, and the M (M is an integer of 1 or more) power splitters 57 connected to the transmission line 54b are referred to as power splitters 57b-1 to 57b-M. The multiplexer 82 and demultiplexer 83 connected to power splitter 57a-n (n is an integer greater than or equal to 1 and less than or equal to N) will be referred to as multiplexer 82a-n and demultiplexer 83a-n, respectively, and the multiplexer 82 and demultiplexer 83 connected to power splitter 57b-m (m is an integer greater than or equal to 1 and less than or equal to M) will be referred to as multiplexer 82b-m and demultiplexer 83b-m, respectively. The optical SW 95 connected to multiplexer 82a-n will be referred to as optical SW 95a-n, and the optical SW 96 connected to demultiplexer 83a-n will be referred to as optical SW 96a-n. The optical SW 95 connected to multiplexer 82b-m will be referred to as optical SW 95b-m, and the optical SW 96 connected to demultiplexer 83b-m will be referred to as optical SW 96b-m.

[0110] Optical SW 1009a and optical SW 1009b are connected by transmission lines 54c and 54d. Port 11-2 of optical SW 1009a connected to transmission line 54c is referred to as port 11a-2-q1, and port 11-2 of optical SW 1009a connected to transmission line 54d is referred to as port 11a-2-q2. Port 11-2 of optical SW 1009b connected to transmission line 54c is referred to as port 11b-2-q1, and port 11-2 of optical SW 1009b connected to transmission line 54d is referred to as port 11b-2-q2.

[0111] In the above configuration, the optical SW 95b-m outputs optical signals of different wavelengths transmitted by the optical transmitter 42 of each subscriber device 40 to ports of the multiplexer 82b-m corresponding to each wavelength. The multiplexer 82b-m receives optical signals of different wavelengths transmitted by the optical transmitter 42 of each subscriber device 40 via the optical SW 95b-m and outputs a wavelength-multiplexed optical signal by multiplexing the received optical signals. The power splitter 57b-m multiplexes the wavelength-multiplexed optical signal output by the multiplexer 82b-m with a wavelength-multiplexed optical signal transmitting on the transmission line 54b in the direction from port 11b-1-p2 to port 11b-1-p1, and outputs the result.

[0112] Port 11b-1-p1 of optical SW 1009b inputs a wavelength-multiplexed optical signal from transmission path 54b and outputs it from port 11b-2-q1. Port 11a-2-q1 of optical SW 1009a inputs the wavelength-multiplexed optical signal output from port 11b-2-q1 of optical SW 1009b via transmission path 54c. Optical SW 1009a outputs the wavelength-multiplexed optical signal input from port 11a-2-q1 to transmission path 54a from port 11a-1-p1.

[0113] The power splitter 57a-n splits the wavelength-multiplexed optical signal transmitted through the transmission line 54a from port 11a-1-p1 to port 11a-1-p2 and outputs the split wavelength-multiplexed optical signal to the demultiplexer 83a-n. The demultiplexer 83a-n splits the wavelength-multiplexed optical signal received from the power splitter 57a-n and outputs the split optical signal to the optical SW 96a-n from a port corresponding to the wavelength. The optical SW 96a-n outputs the optical signal of each wavelength input from the demultiplexer 83a-n to the optical receiver 43 of the subscriber device 40 that receives the optical signal of that wavelength.

[0114] On the other hand, the optical SW95a-n outputs optical signals of different wavelengths transmitted by the optical transmitters 42 of each subscriber device 40 to ports of the multiplexer 82a-n corresponding to each wavelength. The multiplexer 82a-n receives optical signals of different wavelengths transmitted by the optical transmitters 42 of each subscriber device 40 via the optical SW95a-n and outputs a wavelength-multiplexed optical signal by multiplexing the received optical signals. The power splitter 57a-n multiplexes the wavelength-multiplexed optical signal output by the multiplexer 82a-n with a wavelength-multiplexed optical signal transmitting on the transmission path 54a in the direction from port 11a-1-p1 to port 11a-1-p2, and outputs the result.

[0115] Port 11a-1-p2 of optical SW 1009a receives a wavelength-multiplexed optical signal from transmission path 54a and outputs it from port 11a-2-q2. Port 11b-2-q2 of optical SW 1009b receives a wavelength-multiplexed optical signal output from port 11a-2-q2 of optical SW 1009a via transmission path 54d. Optical SW 1009b outputs the wavelength-multiplexed optical signal received from port 11b-2-q2 to transmission path 54b via port 11b-1-p2.

[0116] The power splitter 57b-m splits the wavelength-multiplexed optical signal transmitted through the transmission line 54b in the direction from port 11b-1-p2 to port 11b-1-p1 and outputs the split wavelength-multiplexed optical signal to the demultiplexer 83b-m. The demultiplexer 83b-m splits the wavelength-multiplexed optical signal received from the power splitter 57b-m and outputs the split optical signal to the optical SW 96b-m from a port corresponding to the wavelength. The optical SW 96b-m outputs the optical signal of each wavelength input from the demultiplexer 83b-m to the optical receiver 43 of the subscriber device 40 that receives the optical signal of that wavelength.

[0117] Although FIG. 23 shows a case where the optical signal is transmitted counterclockwise, it may be transmitted clockwise, or two cores on the left and right may be combined into one set for redundancy.

[0118] Next, a connection configuration when the number of user connections increases will be described. Fig. 24 is a diagram showing an example in which scalability of optical SWs is required. Fig. 24 shows N (N is an integer equal to or greater than 1) optical SWs 1010-1 to 1010-N. The optical SWs 10a to 10h described above can be used as the optical SWs 1010-1 to 1010-N. Fig. 24 shows an example in which N=4. In the figure, an ONU #np serving as a subscriber device 40 is connected to a port 11-1-p of the optical SW 1010-n (n is an integer equal to or greater than 1 and equal to or less than N). A port 11-2-q of the optical SW 1010-n is connected to an uplink. The uplink is a transmission path 50-2 connected to an upper network.

[0119] When the number of users becomes enormous and the number of ONUs increases, the scale may exceed the capacity of the optical SW 1010. In this embodiment, even in such a case, the connection configuration shown in Fig. 25 or 26 realizes the same functions as when the number of users is small, such as connection by selecting an arbitrary uplink and optical loopback to an arbitrary subscriber device.

[0120] 25 is a diagram showing an example of optical SW scalability using a mesh configuration. Some ports 11-1 of an optical SW 1010 are connected to an ONU via a transmission path 50-1, and some ports 11-2 are connected to an uplink transmission path 50-2. Furthermore, some ports 11-1 of an optical SW 1010 are connected to some ports 11-2 of other optical SWs 1010 via a transmission path 50-3. In this diagram, one optical SW 1010 is connected to all other optical SWs 1010.

[0121] The multiple ports 11-1 of the optical SW 1010 are referred to as ports 11-1-1, 11-1-2, 11-1-3, ..., 11-1-p1, 11-1-p2, 11-1-p3, and the multiple ports 11-2 of the optical SW 1010 are referred to as ports 11-2-1, 11-2-2, 11-2-3, ..., 11-2-q1, 11-2-q2, 11-2-q3.

[0122] 25, ports 11-1-1, 11-1-2, 11-1-3, ... of optical SW 1010-n (n is an integer between 1 and N) are connected to ONU #n1, ONU #n2, ONU #n3, ..., and ports 11-2-1, 11-2-2, 11-2-3, ... are connected to transmission paths 50-2 of uplink #n1, uplink #n2, uplink #n3, .... Furthermore, optical SW 1010-n is connected to ports 11-1 of all other optical SWs 1010-j (j ≠ n, j is an integer between 1 and N) via some ports 11-2. For example, port 11-2-q1 of optical SW1010-1 is connected to port 11-1-p1 of optical SW1010-2, port 11-2-q2 of optical SW1010-1 is connected to port 11-1-p1 of optical SW1010-3, and port 11-2-q3 of optical SW1010-1 is connected to port 11-1-p1 of optical SW1010-4. Also, port 11-2-q1 of optical SW1010-2 is connected to port 11-1-p1 of optical SW1010-1, port 11-2-q2 of optical SW1010-2 is connected to port 11-1-p2 of optical SW1010-3, and port 11-2-q3 of optical SW1010-2 is connected to port 11-1-p2 of optical SW1010-4. The optical SW 1010-n may be connected to ports 11-1 of some of the optical SWs 1010-j (j≠n, j is an integer between 1 and N) among all other optical SWs 1010-j via some ports 11-2.

[0123] For example, when ONU #11 transmits an upstream optical signal with wavelength λ1 destined for uplink #41, optical SW 1010-1 receives the optical signal at port 11-1-1 and outputs it from port 11-2-q3. Port 11-1-p1 of optical SW 1010-4 receives the optical signal with wavelength λ1 output from port 11-2-q3 of optical SW 1010-1 and outputs it from port 11-2-1.

[0124] When ONU #12 transmits an upstream optical signal with wavelength λ2 addressed to ONU #31, optical SW 1010-1 receives the optical signal from port 11-1-2 and outputs it from port 11-2-q2. Port 11-1-p1 of optical SW 1010-3 receives the optical signal from port 11-2-q2 of optical SW 1010-1. Optical SW 1010-3 performs return communication on the optical signal with wavelength λ2 received from port 11-1-p1 in the same manner as optical SW 10b shown in FIG. 3, and outputs it from port 11-1-1.

[0125] 25 shows only upstream optical signals. When performing bidirectional communication, WDM filters are provided in the transmission paths 50-1, 50-2, and 50-3 to separate and transmit upstream and downstream optical signals. The downstream optical signals are connected in the opposite direction to the upstream optical signals described above.

[0126] Fig. 26 is a diagram showing another example of optical SW scalability using a cascade configuration. The configuration shown in Fig. 26 differs from the configuration shown in Fig. 25 in that an optical SW 1010-n (n is an integer between 1 and N) is connected to port 11-1 of any other optical SW 1010-(n+1) via some port 11-2. Note that the optical SW 1010-(N+1) is assumed to be optical SW 1010-1. This allows multiple optical SWs 1010 to be connected in series.

[0127] In Figure 26, ports 11-1-1, 11-1-2, 11-1-3, ... of optical SW1010-n (n is an integer greater than or equal to 1 and less than or equal to N) are connected to ONU#n1, ONU#n2, ONU#n3, ..., and ports 11-2-1, 11-2-2, 11-2-3, ... are connected to transmission paths 50-2 of uplink#n1, uplink#n2, uplink#n3, .... Furthermore, port 11-2-q1 of optical SW1010-n is connected to port 11-1-p1 of optical SW1010-(n+1), port 11-2-q2 of optical SW1010-n is connected to port 11-1-p2 of optical SW1010-(n+1), and port 11-2-q3 of optical SW1010-n is connected to port 11-1-p3 of optical SW1010-(n+1).

[0128] For example, when ONU #11 transmits an upstream optical signal with wavelength λ1 destined for uplink #41, optical SW 1010-1 inputs the optical signal from port 11-1-1 and outputs it from port 11-2-q1. Port 11-1-p1 of optical SW 1010-2 inputs the optical signal output from port 11-2-q1 of optical SW 1010-1 and outputs it from port 11-2-q1 according to wavelength λ1. Port 11-1-p1 of optical SW 1010-3 inputs the optical signal output from port 11-2-q1 of optical SW 1010-2 and outputs it from port 11-2-q1 according to wavelength λ1. Port 11-1-p1 of optical SW 1010-4 inputs the optical signal output from port 11-2-q1 of optical SW 1010-3 and outputs it from port 11-2-q1 according to wavelength λ1.

[0129] When ONU #12 transmits an upstream optical signal with wavelength λ2 addressed to ONU #31, optical SW 1010-1 outputs the optical signal input from port 11-1-2 from port 11-2-q2. Port 11-1-p2 of optical SW 1010-2 inputs the optical signal output from port 11-2-q2 of optical SW 1010-1. Optical SW 1010-2 outputs the optical signal input from port 11-1-p2 from port 11-2-q2 according to wavelength λ2. Port 11-1-p2 of optical SW 1010-3 inputs the optical signal output from port 11-2-q2 of optical SW 1010-2. Optical SW 1010-3 performs return communication on the optical signal input from port 11-1-p2 according to wavelength λ2 in the same manner as optical SW 10b shown in FIG. 3, and outputs the signal from port 11-1-1.

[0130] 26 shows only upstream optical signals. When performing bidirectional communication, WDM filters are provided in the transmission paths 50-1, 50-2, and 50-3 to separate and transmit upstream and downstream optical signals. The downstream optical signals are connected in the opposite direction to the upstream optical signals described above.

[0131] In the following embodiments, examples of optical access systems using optical switches having the above-described functions will be described.

[0132] (First embodiment) 27 is a diagram showing an example of the configuration of the optical access system 100. The optical access system 100 includes an optical gateway (GW) 200 and an operation system (OPS) 300. A subscriber device 40 is communicably connected to an upper network such as the optical communication network 30 shown in FIG. 1 via the optical access system 100.

[0133] The subscriber device 40 is a device on the optical subscriber side. The subscriber device 40 is connected to the optical gateway 200 via a transmission path 501. The transmission path 501 is, for example, an optical fiber. The optical gateway 200 is a device located within a communication station. The subscriber device 40, indicated by the symbol N1, and the optical gateway 200 are connected via, for example, the transmission path 501 and a power splitter 502. The network configuration connecting the subscriber device 40 to the optical gateway 200 may be various network topologies, such as a PtoP (point-to-point) configuration, a PON configuration, or a bus type. For example, the transmission path 501 may include a power splitter 502, and multiple subscriber devices 40 may be connected to one transmission path 501. The optical gateway 200 is connected to other stations or a core network via transmission paths 511 and 512. The transmission paths 511 and 512 are, for example, optical fibers. The transmission path 511 transmits upstream signals, and the transmission path 512 transmits downstream signals. The transmission path 511 and the transmission path 512 are examples of multiplexed communication transmission paths that transmit wavelength-multiplexed optical signals. The connection from the optical GW 200 indicated by the symbol N2 to another station or a core network is, for example, by the optical fiber transmission path 511 or the transmission path 512, and the connection between the stations is fully meshed. In this embodiment, an example will be described in which the optical GW 200 is installed in a station for station A, and is connected to an optical communication device installed in a station for station B and an optical communication device installed in a station for station C via an optical communication network 30 or the like. The optical communication devices for station B and station C to which the optical GW 200 is connected may be the optical GW 200.

[0134] The subscriber device 40 is connected to the optical GW 200 via a transmission path 501. The subscriber device 40 has an optical transceiver 41. The optical transceiver 41 is a wavelength-tunable optical transmitter / receiver. The optical transceiver 41 is, for example, an optical transceiver that converts optical signals into electrical signals and vice versa. The subscriber device 40 can select and set its own wavelength in the optical transceiver 41 depending on the transmission / reception destination. The subscriber device 40 sets the wavelength to be used in the optical transceiver 41 according to instructions received from the optical GW 200. M (M is an integer greater than or equal to 1) subscriber devices 40 connected to the optical GW 200 are referred to as subscriber devices 40-1 to 40-M.

[0135] The optical GW 200 includes an optical SW 210, a wavelength multiplexer / demultiplexer 220, a control device 230, a multiplexer 241, a demultiplexer 242, a branching unit 250, and a monitoring device 260. The branching unit 250 and the monitoring device 260 are examples of a monitoring unit.

[0136] The optical SW210 has multiple input / output ports (hereinafter referred to as "ports") and connects two or more ports. The optical SW210 can freely switch the optical path between ports. A port that inputs and outputs upstream signals is referred to as an upstream port, and a port that inputs and outputs downstream signals is referred to as a downstream port. Each port of the optical SW210 is connected to a transmission path.

[0137] The wavelength multiplexer / demultiplexer 220 performs uplink / downlink demultiplexing, which separates upstream and downstream signals by wavelength. The wavelength multiplexer / demultiplexer 220 receives an upstream optical signal transmitted from the subscriber device 40 via a transmission path 501 and outputs it to the optical SW210 via a transmission path 521. The wavelength multiplexer / demultiplexer 220 also receives a downstream optical signal transmitted from the optical SW210 via a transmission path 522 and outputs it to the subscriber device 40 via the transmission path 501.

[0138] The control device 230 is connected to the upstream and downstream ports of the optical SW 210, which are not connected to the subscriber device 40. The upstream port of the optical SW 210 is connected to a transmission-side port of the control device 230 via a transmission line 531. The downstream port of the optical SW 210 is connected to a transmission-side port of the control device 230 via a transmission line 533. The control device 230 includes a wavelength demultiplexer 231, optical receivers (Rx) 232 for each wavelength channel, and a wavelength tunable transmitter 233. The wavelength demultiplexer 231 is, for example, an AWG (arrayed waveguide grating). The wavelength demultiplexer 231 demultiplexes light input to a receiving-side port via a transmission line 540 into wavelengths. The wavelength demultiplexer 231 outputs each demultiplexed light to an optical receiver 232, which receives an optical signal of that wavelength. The wavelength tunable transmitter 233 includes a wavelength tunable laser diode (LD) that generates light of a tunable wavelength. The tunable wavelength transmitter 233 transmits an optical signal with a tunable wavelength using light generated by a tunable wavelength laser diode. The tunable wavelength transmitter 233 outputs the optical signal using the generated light from a port on the transmitting side to a transmission line 533.

[0139] The multiplexer 241 multiplexes upstream optical signals of different wavelengths output by the optical SW210 from each of the multiple transmission paths 541, and outputs the multiplexed signal to a transmission path 511 connected to another terminal. The demultiplexer 242 inputs an optical signal transmitted from one of the other terminals from a transmission path 512, and demultiplexes the input downstream optical signal by wavelength. The demultiplexer 242 inputs each of the demultiplexed downstream optical signals to the optical SW210 via multiple transmission paths 542 connected to upstream ports corresponding to the wavelengths of the optical signals.

[0140] The branching unit 250 is provided on the transmission line 511 and the transmission line 512. The branching unit 250 has power splitters 251 and 252. The power splitter 251 branches an upstream optical signal transmitted on the transmission line 511 and inputs the signal to the optical SW 210 via the transmission line 551. The power splitter 252 branches a downstream optical signal transmitted on the transmission line 512 and inputs the signal to the optical SW 210 via the transmission line 552.

[0141] The monitoring device 260 includes a wavelength demultiplexer 261 and optical receivers (Rx) 262 for each wavelength. The wavelength demultiplexer 261 is connected to the optical SW 210 via a transmission line 560. The optical SW 210 outputs an optical signal input from a port connected to the transmission line 541 or 542 to a port connected to the transmission line 560. As a result, the wavelength demultiplexer 261 receives the optical signal branched by the branching unit 250. The wavelength demultiplexer 261 demultiplexes the input optical signal by wavelength. The wavelength demultiplexer 261 outputs each of the demultiplexed light beams to an optical receiver 262 that receives an optical signal of that wavelength. The monitoring device 260 monitors the status of communications transmitted and received by the subscriber device 40 using the optical signals received by the optical receiver 262.

[0142] The OPS 300 includes an optical GW control unit 301 and a management DB 350. The optical GW control unit 301 is connected to the optical GW 200. The optical GW control unit 301 includes a wavelength control unit 310 and an optical SW control unit 320. The wavelength control unit 310 stores information indicating the optical wavelengths used by each user (or each service). The wavelength control unit 310 refers to this information and dynamically allocates wavelengths to be used by each user. The wavelength control unit 310 may be installed in a building different from that of the optical GW 200, and may be connected to the optical SW 210 and the optical SW control unit 320 via a network. The wavelength control unit 310 manages and controls, in real time, information on which users are connected to which ports of the optical SW 210 and which wavelengths they are using, by sharing each connection information.

[0143] The optical GW control unit 301 is also connected to a management database (DB) 350. The optical GW control unit 301 exchanges information about users and wavelengths in use with the management DB 350. The management DB 350 stores wavelengths in use and destination information for each user. The destination is expressed as, for example, destination A, destination B, etc. The management DB 350 manages information about all users connected to the optical access system 100.

[0144] 28 is a diagram showing an example of the SW connection table. The SW connection table shows the connection destination of each port of the optical SW 210. In other words, the port through which an optical signal is input or output can be used as information for identifying the source or destination of the optical signal, such as the subscriber device 40, the control device 230, the branching unit 250, the monitoring device 260, or the ground.

[0145] The wavelength table includes a user wavelength table and an inter-office wavelength table. 29 is a diagram showing an example of a user wavelength table. The user wavelength table indicates the wavelengths used by each user for transmission, the wavelengths used for reception, the available wavelengths not used for transmission or reception, and the wavelengths that cannot be used due to a malfunction. The management DB 350 may manage a wavelength table for each transmission path connected to the optical SW 210.

[0146] 30 is a diagram showing an example of an inter-office wavelength table, which indicates wavelengths that a certain terminal is using for communication with each of the other terminals, free wavelengths that are not used for communication with each of the other terminals, and wavelengths that cannot be used for communication with each of the other terminals due to a failure.

[0147] Next, an example of the configuration of the subscriber device 40 will be described with reference to Figures 31 and 32. Figure 31 is a configuration diagram of a dual-core subscriber device 401. The subscriber device 401 has an optical transceiver 411. The optical transceiver 411 is equipped with a tunable light source 451, a tunable filter 452, and a receiver 453. The tunable light source 451 is an example of an optical transmitting unit, and the tunable filter 452 and the receiver 453 are examples of an optical receiving unit. The tunable light source 451 outputs light of a set wavelength. The wavelength set in the tunable light source 451 is tunable. The tunable filter 452 receives an optical signal from the transmission path 501 and passes the light of the set wavelength to the receiver 453. The wavelength set in the tunable filter 452 is tunable. The receiver 453 receives the optical signal passed by the tunable filter 452. The tunable light source 451 can output a main signal (or a signal obtained by superimposing a control signal on the main signal) by, for example, a direct modulation method. Alternatively, the tunable light source 451 can further have an external modulator and output a main signal (or a signal obtained by superimposing a control signal on the main signal) by using the external modulator. The receiving subscriber device 401 may be configured without using the tunable filter 452 depending on the configuration of the optical gateway, the multiplexing method, etc.

[0148] FIG. 32 is a configuration diagram of a single-core subscriber unit 402. The subscriber unit 402 has an optical transceiver 412. The optical transceiver 412 shown in FIG. 32 differs from the optical transceiver 411 shown in FIG. 31 in that it further includes a WDM filter 454. The WDM filter 454 separates upstream and downstream signals by wavelength. The WDM filter 454 outputs light generated by a tunable light source 451 to a transmission path 501 and outputs an optical signal input from the transmission path 501 to the tunable filter 452. The tunable light source 451 can output a main signal (or a signal obtained by superimposing a control signal on the main signal) by, for example, direct modulation. Alternatively, the subscriber unit 402, like the subscriber unit 401, can further include an external modulator and output a main signal (or a signal obtained by superimposing a control signal on the main signal) using the external modulator. The receiving-side subscriber device 402 may be configured without using the wavelength tunable filter 452 depending on the optical gateway configuration, multiplexing method, and the like.

[0149] Here, the operation when a new subscriber device 40 is connected will be described. Fig. 33 is a flowchart showing the initial setting process of the optical access system 100 when a new subscriber device 40-1 is connected. Using Fig. 27 and Fig. 33, the operation of the optical access system 100 when a new subscriber device 40-1 is connected to the optical GW 200 will be described. It is assumed that the control device 230 has confirmed in advance which port of the optical SW 210 each port of the wavelength demultiplexer 261 (AWG) of the control device 230 is connected to.

[0150] First, before connecting a new subscriber device 40-1, a user application is made. For example, the user application allows communication between destination A and destination B. Based on the user application, the service provider registers user information, initial destination information, and the like in the management DB 350 of the OPS 300 (step S1). The user information is, for example, information that enables the optical transceiver 41 to obtain wavelengths that can be used. The OPS 300 refers to the SW connection table and assigns a port of the optical SW 210 to connect the subscriber device 40-1 from among the available ports of the optical SW 210. Here, an upstream port and a downstream port are assigned. The OPS 300 registers information indicating that the assigned port is connected to the subscriber device 40-1 in the SW connection table (step S2). The optical SW control unit 320 of the OPS 300 controls the optical SW 210 to transmit and receive optical signals between the port assigned to the subscriber device 40-1 and the port to which the control device 230 is connected.

[0151] When new subscriber device 40-1 is connected, subscriber device 40-1 performs initialization processing and transmits a connection request (register request) by optical signal (step S3). Subscriber device 40-1 automatically performs initialization processing before or immediately after connection. The wavelength multiplexer / demultiplexer 220 inputs the connection request from the transmission path 501 and outputs it to the optical SW 210 via the transmission path 521. The optical SW 210 transmits the connection request input from the port connected to subscriber device 40-1 to the output port to which the control device 230 is connected. The control device 230 inputs the connection request from the receiving port via the transmission path 531. The control device 230 analyzes the input optical signal and checks whether there are any problems with the initial setting wavelength or optical power (step S4).

[0152] If there is a problem with the wavelength or optical power, the control device 230 transmits a restart or initialization instruction to the subscriber device 40-1. After the restart or initialization, the process returns to step S3, and the subscriber device 40-1 transmits a connection request again.

[0153] The control device 230 analyzes the optical signal received from the subscriber device 40-1, and if it is confirmed that there is no problem, outputs a connection request to the optical GW control unit 301. The optical GW control unit 301 registers information about the subscriber device 40-1 in the management DB 350. The connection request includes information about the connection source, information about the connection destination, and the type of signal to be transmitted. The connection source information, for example, uses address information such as a Medium Access Control (MAC) address. The connection destination information, for example, uses destination address information. The type of signal to be transmitted, for example, uses service or modulation method. The wavelength control unit 310 registers the connection source information in the management DB 350 based on this information. As a result, the user identification of the subscriber device 40-1 and the fact that the wavelength available to the subscriber device 40-1 is available are set in the user wavelength table. Furthermore, the wavelength control unit 310 compares the connection information stored in the management DB 350 and calculates the optimal route between the subscriber device 40-1 and the communication destination, such as between destination A and destination B. The wavelength control unit 310 searches for an available wavelength indicated in the inter-office wavelength table according to the calculated route. The wavelength control unit 310 selects a wavelength to be used by the subscriber device 40-1 from the available wavelengths, and transmits information about the selected wavelength to the control device 230 (step S5).

[0154] The other subscriber device 40 that is the destination of communication with the subscriber device 40-1 is referred to as the destination subscriber device 40. In this case, the wavelength control unit 310 selects a transmission wavelength, which is a wavelength that the subscriber device 40-1 will use to transmit an optical signal to the destination subscriber device 40, and a reception wavelength, which is a wavelength that the subscriber device 40-1 will use to receive an optical signal from the destination subscriber device 40. The wavelength control unit 310 transmits the selected transmission wavelength and reception wavelength to the control device 230 as the wavelengths to be used by the subscriber device 40-1. Note that if the subscriber device 40-1 only transmits to the destination subscriber device 40, the wavelength control unit 310 does not need to select a reception wavelength. Also, if the subscriber device 40-1 only receives from the destination subscriber device 40, the wavelength control unit 310 does not need to select a transmission wavelength.

[0155] The control device 230 transmits wavelength information as follows: The tunable wavelength transmitter 233 of the control device 230 transmits a wavelength instruction, which includes information about the wavelength selected by the wavelength control unit 310, using an optical signal with a wavelength destined for the subscriber device 40-1. The optical SW 210 outputs the optical signal input from the port connected to the tunable wavelength transmitter 233 to the transmission path 522 connected to the subscriber device 40-1. The wavelength multiplexer / demultiplexer 220 inputs the optical signal input from the optical SW 210 via the transmission path 522 into the transmission path 501. The subscriber device 40-1 receives the optical signal transmitted through the transmission path 501. The subscriber device 40-1 sets the oscillation wavelength of the optical transceiver 41 in accordance with the wavelength instruction indicated by the received optical signal (step S6). That is, the subscriber device 40-1 sets the oscillation wavelength of the optical transceiver 41 (tunable wavelength light source 451) so that the subscriber device 40-1 transmits the optical signal at the transmission wavelength set in the wavelength instruction. If the wavelength instruction specifies a receiving wavelength, the subscriber device 40-1 sets the optical transceiver 41 (tunable filter 452) to receive a wavelength signal of the receiving wavelength.

[0156] The optical transceiver 41 of the subscriber device 40-1 transmits a notification signal, using an optical signal of the specified wavelength, notifying that the wavelength has been set. The notification signal is transmitted to the control device 230 in the same manner as the request signal. Based on the received notification signal, the control device 230 checks whether the specified wavelength is set correctly, whether the output power is sufficient, and so on (step S7). If the control device 230 determines that there are no problems as a result of the check, it transmits an authorization notification to the subscriber device 40-1 by optical signal, indicating that it is permitted to start communication. The authorization notification is transmitted to the subscriber device 40-1 in the same manner as the wavelength instruction.

[0157] The optical SW control unit 320 transmits connection information of the optimal port in the optical SW 210 according to the destination of the subscriber device 40-1 to the optical SW 210. Based on the connection information, the optical SW 210 sets the upstream port and downstream port of the subscriber device 40-1 in accordance with an instruction from the optical SW control unit 320 (step S8).

[0158] Furthermore, the optical access system 100 controls the timing of path switching within the optical SW 210 so that it occurs after the control device 230 transmits permission to start communication to the subscriber device 40-1. For example, it is assumed that the time required for path switching in the optical SW 210 is known in advance. In this case, the control device 230 waits for the time required for the optical SW 210 to actually switch paths from when it receives the instruction to switch paths until the subscriber device 40-1 actually starts communication after receiving permission to start communication, and then issues an instruction to start communication. After communication starts, the monitoring device 260 of the optical GW 200 checks the communication status between the opposing subscriber devices (step S9). The monitoring device 260 notifies the OPS 300 of the check result. If the check is unsuccessful, the OPS 300 performs a procedure to isolate the cause.

[0159] The connection request transmitted by the subscriber device 40-1 and the control signal transmitted by the control device 230 to the subscriber device 40-1 are optical signals slower than the main signal. For the control signal, a protocol-free control signal (control method) such as AMCC can be used.

[0160] Furthermore, the OPS 300 instructs the destination subscriber device 40 to use the transmission wavelength of the subscriber device 40-1 as the reception wavelength of the destination subscriber device 40 and the reception wavelength of the subscriber device 40-1 as the transmission wavelength of the destination subscriber device 40. For example, in the optical GW control unit 301 that controls the optical GW 200 in which the destination subscriber device 40 is accommodated, the wavelength control unit 310 instructs the control device 230 to transmit a wavelength instruction that sets the reception wavelength and transmission wavelength of the destination subscriber device 40. The destination subscriber device 40 receives the wavelength instruction from the control device 230 using a control signal, and sets the reception wavelength and transmission wavelength in the optical transceiver 41 according to the received wavelength instruction. That is, when the transmission wavelength is set in the wavelength instruction, the destination subscriber device 40 sets the oscillation wavelength of the optical transceiver 41 (tunable wavelength light source 451) so as to transmit an optical signal at the transmission wavelength. If the wavelength instruction specifies a receiving wavelength, the destination subscriber device 40 sets the optical transceiver 41 (tunable filter 452) to receive a wavelength signal of the receiving wavelength.

[0161] The optical access system 100 may not perform the user application in step S1, and may transmit and receive information to be registered in the management DB 350 in response to the user application between the new subscriber device 40-1 and the optical GW control unit 301. This enables the subscriber device 40-1 to communicate with other subscriber devices 40 without performing a user application. Transmission and reception of information between the subscriber device 40-1 and the optical GW control unit 301 is performed via the control device 230, for example, using AMCC.

[0162] The above describes the operation when a new subscriber device is connected. Next, normal communication operations after the new subscriber device is connected will be described using an example in which the subscriber device 40-2 in Figure 27 performs communication.

[0163] First, we will explain upstream communication. The upstream optical signal output by the subscriber device 40-2 is sent to the optical gateway 200 via a transmission path 501. The wavelength multiplexer / demultiplexer 220 of the optical gateway 200 separates the input optical signal into an upstream optical signal and a downstream optical signal based on the wavelength. The upstream optical signal separated by the wavelength multiplexer / demultiplexer 220 is input to the optical switch 210 via a transmission path 521. The optical switch 210 connects the port to which the upstream optical signal is input from the wavelength multiplexer / demultiplexer 220 to another port corresponding to the route to the destination of the subscriber device 40-2, and outputs the optical signal. When the wavelength is used as destination information, the optical switch 210 connects to another port corresponding to the destination specified by the wavelength assigned to the subscriber device 40-2, and outputs the optical signal. The upstream signal output from the optical SW210 is multiplexed in the multiplexer 241 with optical signals of different wavelengths transmitted by other subscriber devices 40, and transmitted to another station (for example, terminal B) via a single transmission path 511. The multiplexers 241 each multiplex wavelength channels for each station, such as terminal B and terminal C. It is also possible to use the same wavelength for terminal B and terminal C by separating the transmission path 511 between terminal B and terminal C.

[0164] Next, downstream communications will be described. Downstream communications are communications from destinations B and C to the subscriber device 40. The downstream optical signals are sent to the optical gateway 200 via a single transmission path 512. The demultiplexer 242 of the optical gateway 200 demultiplexes the downstream optical signals transmitted through the transmission path 512 by wavelength. The demultiplexer 242 inputs each demultiplexed light to a downstream port corresponding to the wavelength of the demultiplexed light via the transmission path 542. The optical switch 210 connects the port to which the downstream optical signal from the demultiplexer 242 is input to another port corresponding to the wavelength, and outputs the optical signal. The wavelength multiplexer / demultiplexer 220 demultiplexes the optical signal input from the optical switch 210 via the transmission path 522 into an upstream optical signal and a downstream optical signal by wavelength. The downstream optical signal demultiplexed by the wavelength multiplexer / demultiplexer 220 is input to the subscriber device 40-2 via the transmission path 501. It is assumed that the wavelength channels transmitted from the optical GW 200 to each station (territorial B, C, etc.) are in the same wavelength band, but different wavelength bands may be used for each station.

[0165] The monitoring device 260 of the optical GW 200 receives the light branched by the branching unit 250. The light branched by the branching unit 250 is the optical signal transmitted and received by each subscriber device 40. The monitoring device 260 monitors the signals transmitted and received by each subscriber device 40 by monitoring the received optical signal. If the monitoring device 260 detects an abnormality such as a wavelength shift, a decrease in output, or a communication abnormality through monitoring, it sends an abnormality detection signal to the optical GW control unit 301. The optical SW control unit 320 of the optical GW control unit 301 controls the optical SW 210 to reconnect the target subscriber device 40 to the control device 230. Then, the optical GW control unit 301 performs allocation processing of a new wavelength different from the wavelength used when the abnormality was detected, just as when a new subscriber device 40 is connected. As a result, when the optical SW 210 receives an optical signal with a changed wavelength from the subscriber device 40, it connects the input optical signal to the port that the subscriber device 40 was identified by the wavelength before the change.

[0166] The optical GW 200 shown in FIG. 27 performs wavelength multiplexing, but as shown in FIGS. 34 and 35, wavelength multiplexing may not be performed. FIG. 34 is a diagram showing an example of the configuration of an optical access system 101. The optical access system 101 shown in FIG. 34 differs from the optical access system 100 shown in FIG. 27 in that it includes an optical GW 201 instead of the optical GW 200. The optical GW 201 differs from the optical GW 200 in that it includes a wavelength multiplexer / demultiplexer 243 and a branching unit 250a instead of the multiplexer 241, demultiplexer 242, and branching unit 250. The optical GW 201 is connected to communication devices in other remote stations via a transmission path 503. One transmission path 503 transmits upstream signals and downstream signals between the optical GW 201 and any one of the remote stations.

[0167] The wavelength multiplexer / demultiplexer 243 separates the input optical signal into an upstream optical signal and a downstream optical signal based on the wavelength. The wavelength multiplexer / demultiplexer 243 separates the upstream optical signal input from the optical SW 210 via the transmission path 543-1 and transmits it to another destination or an upper network via the transmission path 503. The wavelength multiplexer / demultiplexer 243 also separates the downstream optical signal input from another destination via the transmission path 503 and outputs it to the optical SW 210 via the transmission path 543-2.

[0168] The branching unit 250a is provided on the transmission path 503. The branching unit 250a has a power splitter 251a. The power splitter 251a branches the upstream and downstream optical signals transmitted through the transmission path 503. The power splitter 251a inputs the branched upstream optical signal to a port of the optical SW 210 via the transmission path 551a, and inputs the branched downstream optical signal to a port of the optical SW 210 via the transmission path 551b. The optical SW 210 outputs the optical signal input from the port connected to the transmission path 551a and the optical signal input from the port connected to the transmission path 551b from the port connected to the transmission path 560. As a result, the wavelength demultiplexer 261 of the monitoring device 260 receives the optical signals branched by the branching unit 250a.

[0169] Fig. 35 is a diagram showing an example of the configuration of the optical access system 102. The optical access system 102 shown in Fig. 35 differs from the optical access system 101 shown in Fig. 34 in that the optical access system 102 includes an optical GW 202 instead of the optical GW 201. The optical GW 202 differs from the optical GW 201 in that the optical GW 202 includes a wavelength multiplexer / demultiplexer 244, a wavelength multiplexer / demultiplexer 245, and a branching unit 250b instead of the wavelength multiplexer / demultiplexer 243 and branching unit 250a.

[0170] The wavelength multiplexer / demultiplexer 244 separates the signal into an upstream optical signal and a downstream optical signal based on the wavelength. The wavelength multiplexer / demultiplexer 244 inputs the upstream optical signal input from the optical SW 210 via a transmission line 544 to the wavelength multiplexer / demultiplexer 245 via a transmission line 545. The wavelength multiplexer / demultiplexer 244 inputs the downstream optical signal input from the wavelength multiplexer / demultiplexer 245 via a transmission line 546 to the optical SW 210 via the transmission line 544.

[0171] The wavelength multiplexer / demultiplexer 245 separates the signal into an upstream optical signal and a downstream optical signal based on the wavelength. The wavelength multiplexer / demultiplexer 245 transmits the upstream optical signal input from the wavelength multiplexer / demultiplexer 245 via a transmission path 545 to another ground or an upper network via a transmission path 503. The wavelength multiplexer / demultiplexer 245 also inputs the downstream optical signal received via the transmission path 503 to the wavelength multiplexer / demultiplexer 244 via a transmission path 546.

[0172] The branching unit 250b has a power splitter 251b and a power splitter 252b. The power splitter 251b branches an upstream optical signal transmitted through the transmission path 545. The power splitter 251b inputs the branched upstream optical signal to a port of the optical SW 210 via the transmission path 551b. The power splitter 252b branches a downstream optical signal transmitted through the transmission path 546. The power splitter 252b inputs the branched downstream optical signal to a port of the optical SW 210 via the transmission path 552b. The optical SW 210 outputs the optical signal input from the port connected to the transmission path 551b and the optical signal input from the port connected to the transmission path 552b from the port connected to the transmission path 560. As a result, the wavelength demultiplexer 261 of the monitoring device 260 receives the optical signal branched by the branching unit 250b.

[0173] The above-described monitoring device 260 has a receiver configuration including a wavelength demultiplexer 261 and optical receivers 262 for each wavelength. Instead of this receiver configuration, the monitoring device may have a wavelength-tunable optical receiver. Furthermore, the transmitter / receiver of the control device may have a transmitter that is not wavelength-tunable, or may have a receiver configuration without a wavelength demultiplexer. An example of such a configuration will be described using FIG. 36.

[0174] Fig. 36 is a diagram showing a configuration example of an optical access system 103. The optical access system 103 shown in Fig. 36 differs from the optical access system 100 shown in Fig. 27 in that it includes an optical GW 203 instead of the optical GW 200. The optical GW 203 differs from the optical GW 200 in that it includes a control device 235 and a monitoring device 265 instead of the control device 230 and the monitoring device 260. The control device 235 includes an optical receiver 236 and a non-tunable optical transmitter 237. The monitoring device 265 includes a tunable optical receiver 266.

[0175] Furthermore, the monitoring device may be connected via an optical SW different from the above-mentioned optical SW. An example of such a configuration will be described using Fig. 37. Fig. 37 is a diagram showing an example of the configuration of an optical access system 104. The optical access system 104 shown in Fig. 37 differs from the optical access system 103 shown in Fig. 36 in that it includes an optical GW 204 instead of the optical GW 203. The optical GW 204 differs from the optical GW 203 in that it further includes an optical SW 211 and that a monitoring device 265 is connected to the optical SW 211.

[0176] The upstream optical signal separated from the transmission path 511 by the power splitter 251 of the branching unit 250 is input to the optical SW 211 via the transmission path 555, and the downstream optical signal separated from the transmission path 512 by the power splitter 252 is input to the optical SW 211 via the transmission path 555. The optical SW 211 is, for example, a compact optical SW. The optical SW 211 has one port on the monitoring device 260 side and 2M ports on the side to which the optical signal to be monitored is input. 2M is twice the number M of subscriber devices 40 connected to the optical GW 204. Instead of using compact optical SWs, a monitoring device may be provided for each connected terminal, and signals transmitted to and received from all terminals may be monitored for each terminal.

[0177] (Second embodiment) In this embodiment, communication is performed between a plurality of subscriber devices connected to the same optical gateway using a return transmission line. The following will mainly explain the differences from the first embodiment.

[0178] Fig. 38 is a diagram showing an example of the configuration of an optical access system 105. The optical access system 105 shown in Fig. 38 differs from the optical access system 103 shown in Fig. 36 in that it includes an optical GW 205 instead of the optical GW 203. The optical GW 205 differs from the optical GW 203 in that it further includes a multiplexer 247 and a demultiplexer 248 corresponding to destination A where the optical GW 205 is installed. The multiplexer 247 and the demultiplexer 248 are connected by a transmission path 547. The transmission path 547 is a return transmission path.

[0179] Similar to the multiplexer 241, the multiplexer 247 multiplexes upstream optical signals of different wavelengths output by the optical SW 210 from each of the multiple transmission paths 541, and outputs the multiplexed signal to the transmission path 547. Similar to the demultiplexer 242, the demultiplexer 248 demultiplexes the downstream optical signal input from the transmission path 547 by wavelength. The demultiplexer 248 inputs each of the demultiplexed downstream optical signals to the optical SW 210 via the multiple transmission paths 542 connected to the downstream ports corresponding to the wavelengths of the optical signals. In addition, the transmission path 547 is provided with a branching unit 250.

[0180] In the first embodiment, a subscriber device connected to destination A is connected to a port for connecting to destination B or destination C via an optical SW. In this embodiment, another set of a multiplexer 241 and a demultiplexer 242 is added, which is the same as the set of multiplexer 241 and demultiplexer 242 connected to destination B or destination C. This added set is a multiplexer 247 and a demultiplexer 248. The output port of the added multiplexer 247 is connected to the input port of the added demultiplexer 248 by a transmission path 547. This configuration allows a signal output from a subscriber device 40 to be input again to the optical SW 210. As a result, the optical GW 205 returns an optical signal output from a certain subscriber device 40, and the signal is input again to the optical SW 210 as a downstream signal. By connecting this returned signal to another subscriber device 40 within the optical SW 210, return communication, that is, communication between subscriber devices 40 connected to the same optical GW 205, is possible.

[0181] For example, a state will be described in which subscriber device 40-2 and subscriber device 40-M are communicating. Assume that K (K is an integer of 2 or more) upstream ports of optical SW210 corresponding to destination A are each connected to multiplexer 247 by transmission line 541, and K downstream ports of optical SW210 corresponding to destination A are each connected to demultiplexer 248 by transmission line 542. Then, the k-th (k is an integer of 1 to K) upstream port and downstream port of the K downstream ports and upstream ports corresponding to destination A transmits wavelength λ k The upstream optical signal of wavelength λ1 output from the subscriber device 40-2 is connected to the first upstream port corresponding to destination A. The input optical signal is returned by the transmission line 547 and input again to the optical SW 210 as a downstream optical signal from the first downstream port corresponding to destination A. The optical SW control unit 320 sets a route within the optical SW 210 so that the optical signal is transmitted to the subscriber device 40-M according to the wavelength. Similarly, the upstream optical signal of wavelength λ1 output from the subscriber device 40-M is connected to the first upstream port corresponding to destination A. The input optical signal is returned by the transmission line 547 and input again to the optical SW 210 as a downstream optical signal from the first downstream port corresponding to destination A. The optical SW control unit 320 sets a route within the optical SW 210 so that the optical signal is transmitted to the subscriber device 40-M according to the wavelength. kThe upstream optical signal of is connected to the kth upstream port corresponding to destination A. The input optical signal is returned by the transmission path 547 and input again to the optical SW 210 as a downstream optical signal from the kth downstream port corresponding to destination A. The optical SW control unit 320 sets a route within the optical SW 210 so that the optical signal is transmitted to the subscriber device 40-2 according to its wavelength. This allows communication between subscriber device 40-2 and subscriber device 40-M.

[0182] Another configuration of this embodiment will be described with reference to Fig. 39 and Fig. 40. Fig. 39 is a diagram showing an example of the configuration of an optical access system 106. The optical access system 106 shown in Fig. 39 differs from the optical access system 105 shown in Fig. 38 in that it includes an optical GW 206 instead of the optical GW 205. The optical GW 206 differs from the optical GW 205 in that it does not include a multiplexer 247 or a demultiplexer 248, and is configured to loop back signals by directly connecting the upstream port and downstream port for destination A of the optical SW 210 by a transmission line 548 without wavelength multiplexing.

[0183] Fig. 40 is a diagram showing an example of the configuration of an optical access system 107. The optical access system 107 shown in Fig. 40 differs from the optical access system 105 shown in Fig. 38 in that it includes an optical GW 207 instead of the optical GW 205. The optical GW 207 differs from the optical GW 205 in that it includes a power splitter 270 instead of the demultiplexer 248. The power splitter 270 splits the downstream optical signal input from the multiplexer 247 via a transmission path 547 into multiple signals, and inputs the signals to the optical SW 210 via multiple transmission paths 542.

[0184] A power splitter may be provided after the demultiplexer 248 of the optical GW 205 in Fig. 38. The power splitter splits the optical signal demultiplexed by the demultiplexer 248 into multiple signals, which are input to different ports of the optical SW 210. This enables multicast communication of return communication.

[0185] Although the differences with the optical access system 103 have been explained above, it is also possible to apply the differences to the optical access systems 100, 101, and 102.

[0186] (Third embodiment) The optical access system of this embodiment performs multicast communication. The following description will focus on the differences between this embodiment and the first and second embodiments.

[0187] First, multicasting of downstream communication will be described with reference to Fig. 41. Fig. 41 is a diagram showing an example of the configuration of an optical access system 108. The optical access system 108 shown in Fig. 41 differs from the optical access system 107 shown in Fig. 40 in that it includes an optical GW 208 instead of the optical GW 207. The optical GW 208 differs from the optical GW 207 in that it further includes a transmission path 549 that connects the return port of the optical SW 210.

[0188] A case where a downstream optical signal transmitted from the terminal C is multicast will be described. The optical SW control unit 320 controls the port that inputs the downstream optical signal from the terminal C to be connected to the return port to which the transmission line 549 is connected, according to the wavelength. As a result, the downstream optical signal from the terminal C transmits through the transmission line 549 and is input again to the optical SW 210 as an upstream signal to the terminal A. Similarly to the second embodiment, the optical SW control unit 320 also controls the downstream optical signal input from the return port to be connected to the port for the upstream signal to the terminal A. As a result, the optical signal that is returned through the transmission line 549 and input to the optical SW 210 is output to a port connected to the multiplexer 247. The multiplexer 247 multiplexes the optical signals output from the optical SW 210 by each of the multiple transmission lines 541 and outputs the multiplexed signal to the transmission line 547. The optical signal output to the transmission line 547 is branched into multiple optical signals by the power splitter 270. The power splitter 270 inputs the multiple branched optical signals to the optical SW 210 as downstream signals to destination A via multiple transmission paths 542. The optical SW 210 outputs the optical signals input from each transmission path 542 to ports connected to subscriber devices 40 according to their wavelengths. This enables multicasting of downstream signals.

[0189] Next, multicasting of upstream communication will be described with reference to Fig. 42. Fig. 42 is a diagram showing an example of the configuration of an optical access system 109. The optical access system 109 shown in Fig. 42 differs from the optical access system 103 shown in Fig. 36 in that it includes an optical GW 209 instead of the optical GW 203. The optical GW 209 differs from the optical GW 203 in that it further includes a transmission path 570 that connects a return port to the optical SW 210, and a power splitter 271 for multicasting. The power splitter 271 is connected to the optical SW 210 via a transmission path 572 and a plurality of transmission paths 573.

[0190] A case where an upstream optical signal transmitted from destination A is multicast will be described. The optical SW control unit 320 controls the port that inputs the upstream optical signal from destination A to be connected to the return port connected to the transmission path 570, according to the wavelength. As a result, the upstream optical signal from destination A transmits through the transmission path 570 and is input again to the optical SW 210. The optical SW control unit 320 also controls the optical signal input from the return port to be output to the port connected to the power splitter 271. As a result, the optical signal that has been returned through the transmission path 570 and input to the optical SW 210 is output to the transmission path 572. The optical signal output to the transmission path 572 is branched into multiple optical signals by the power splitter 271. The power splitter 271 inputs the branched multiple optical signals to the optical SW 210 as upstream signals via multiple transmission paths 573. The optical SW 210 outputs the optical signals input from each transmission line 573 to a port connected to either terminal B or terminal C, depending on the wavelength. This makes it possible to multicast upstream signals.

[0191] Next, a configuration for performing point-to-multipoint communication including upstream communication while performing downstream communication multicast will be described with reference to Fig. 43. Fig. 43 is a diagram showing an example of the configuration of an optical access system 110. The optical access system 110 shown in Fig. 43 differs from the optical access system 103 shown in Fig. 36 in that it includes an optical GW 2010 instead of the optical GW 203. The optical GW 2010 differs from the optical GW 203 in that it further includes transmission lines 574 and 575 that connect return ports to the optical SW 210, and power splitters 272 and 273. The power splitter 272 is connected to the optical SW 210 via a transmission line 581 and multiple transmission lines 582. The power splitter 273 is connected to the optical SW 210 via multiple transmission lines 583 and a transmission line 584.

[0192] A case where a downstream optical signal transmitted from the terminal C is multicast will be described. The optical SW control unit 320 controls the port that inputs the downstream optical signal from the terminal C to be connected to the return port to which the transmission path 574 is connected, according to the wavelength. As a result, the downstream optical signal from the terminal C transmits through the transmission path 574 and is input again to the optical SW 210 as an upstream signal to the terminal A. The optical SW control unit 320 also controls the downstream optical signal input from the return port to be output to the port to which the power splitter 272 is connected. As a result, the optical signal that is returned through the transmission path 574 and input to the optical SW 210 is output to the transmission path 581. The optical signal output to the transmission path 581 is branched into multiple optical signals by the power splitter 272. The power splitter 272 inputs the branched multiple optical signals to the optical SW 210 as downstream signals via multiple transmission paths 582. The optical SW 210 outputs the optical signals input from each transmission line 582 to ports connected to the subscriber devices 40 according to the wavelengths, thereby enabling multicasting of downstream signals.

[0193] A case will be described in which an upstream optical signal transmitted from terminal A is transmitted to terminal C. The optical SW control unit 320 controls the port that inputs the upstream optical signal from terminal A to be connected to the port to which the power splitter 273 is connected, depending on the wavelength. As a result, the upstream optical signal from terminal A is output to the transmission path 583. The optical signals output to each of the multiple transmission paths 583 are multiplexed in the power splitter 273. The power splitter 273 inputs the multiplexed optical signal to the optical SW 210 via the transmission path 584. The optical SW 210 controls the optical signal input from the transmission path 584 to be connected to the return port to which the transmission path 575 is connected. As a result, the optical signal transmits through the transmission path 575 and is input again to the optical SW 210. The optical SW 210 outputs the optical signal input from the transmission path 575 to the multiplexer 241 connected to terminal C, depending on the wavelength.

[0194] As described above, by providing two configurations using multicast power splitters, point-to-multipoint communication including not only downstream multicast communication but also upstream communication becomes possible.

[0195] (Fourth embodiment) In this embodiment, communication is performed without separating the uplink signal and the downlink signal. The following mainly describes the differences from the above-described embodiment.

[0196] Fig. 44 is a diagram showing an example of the configuration of an optical access system 111. The optical access system 111 shown in Fig. 44 differs from the optical access system 105 shown in Fig. 38 in that the optical access system 111 includes an optical GW 2011 instead of the optical GW 205. The optical GW 2011 differs from the optical GW 205 in that it does not include the wavelength multiplexer / demultiplexer 220, that it includes a wavelength multiplexer / demultiplexer 249 and a branching unit 253 instead of the multiplexer 241, the branching unit 242 and the branching unit 250, and that it further includes a wavelength multiplexer / demultiplexer 238.

[0197] The wavelength multiplexer / demultiplexer 249 is connected to the optical SW 210 via a plurality of transmission paths 585. The wavelength multiplexer / demultiplexer 249 multiplexes upstream optical signals of different wavelengths output by the optical SW 210 from each of the plurality of transmission paths 585, and outputs the multiplexed signal to a transmission path 504 connected to any other destination. The wavelength multiplexer / demultiplexer 249 also demultiplexes, by wavelength, downstream optical signals input from other destinations via the transmission path 504. The wavelength multiplexer / demultiplexer 249 inputs each of the demultiplexed downstream optical signals to the optical SW 210 via a plurality of transmission paths 585 connected to upstream ports corresponding to the wavelengths of the optical signals.

[0198] The branching unit 253 has a power splitter 254. The power splitter 254 branches an upstream optical signal and a downstream optical signal transmitted through the transmission path 504. The power splitter 254 inputs the branched upstream optical signal to a port of the optical SW 210 via the transmission path 586, and inputs the branched downstream optical signal to a port of the optical SW 210 via the transmission path 587. The optical SW 210 outputs the optical signal input from the port connected to the transmission path 586 or the transmission path 587 to the port connected to the transmission path 560.

[0199] The wavelength multiplexer / demultiplexer 238 is connected to the optical SW 210 via a transmission line 534, and is connected to the control device 235 via transmission lines 531 and 533. The wavelength multiplexer / demultiplexer 238 separates the input optical signal into an upstream optical signal and a downstream optical signal based on the wavelength. The wavelength multiplexer / demultiplexer 238 outputs the upstream optical signal input from the optical SW 210 via the transmission line 534 to the control device 235 via the transmission line 531. The wavelength multiplexer / demultiplexer 238 outputs the downstream optical signal input from the control device 235 via the transmission line 533 to the optical SW 210 via the transmission line 534.

[0200] As described above, the optical GW 2011 does not have a wavelength multiplexer / demultiplexer between the optical SW 210 and the optical subscriber device 40, and does not separate the upstream and downstream signals. This makes it possible to significantly reduce the number of ports used in the optical SW 210 and the amount of information to be managed. Also, as shown in Fig. 45, the part that separates the optical signals to the monitoring device 265 may have the configuration shown in Fig. 35.

[0201] Fig. 45 is a diagram showing an example of the configuration of the optical access system 112 of this embodiment. The optical gateway 2012 of the optical access system 112 shown in Fig. 45 includes a branching unit 255 instead of the branching unit 253 included in the optical gateway 2011 shown in Fig. 44. The branching unit 255 includes a wavelength multiplexer / demultiplexer 256, a wavelength multiplexer / demultiplexer 257, a power splitter 258, and a power splitter 259.

[0202] The wavelength multiplexer / demultiplexer 256 separates the input optical signal into an upstream optical signal and a downstream optical signal based on wavelength. The wavelength multiplexer / demultiplexer 256 outputs the upstream optical signal input from the wavelength multiplexer / demultiplexer 249 to the wavelength multiplexer / demultiplexer 257 via a transmission path 588. The wavelength multiplexer / demultiplexer 256 outputs the downstream optical signal input from the wavelength multiplexer / demultiplexer 257 to the wavelength multiplexer / demultiplexer 249 via a transmission path 589.

[0203] The wavelength multiplexer / demultiplexer 257 separates the signal into an upstream optical signal and a downstream optical signal based on the wavelength. The wavelength multiplexer / demultiplexer 257 outputs the upstream optical signal input from the wavelength multiplexer / demultiplexer 256 via the transmission line 588 to the transmission line 504. The wavelength multiplexer / demultiplexer 257 inputs the downstream optical signal received from another destination via the transmission line 504 to the wavelength multiplexer / demultiplexer 256 via the transmission line 589.

[0204] The power splitter 258 splits an upstream optical signal transmitted through the transmission line 588 and inputs the split signal to a port of the optical SW 210 via the transmission line 586. The power splitter 259 splits a downstream optical signal transmitted through the transmission line 589 and inputs the split signal to a port of the optical SW 210 via the transmission line 587. The optical SW 210 outputs the optical signal input from the port connected to the transmission line 586 or the transmission line 587 to the port connected to the transmission line 560.

[0205] The optical GW2011 shown in Figure 44 performs wavelength multiplexing, but as shown in Figure 46, the signals to be transmitted to each station (terminal B and terminal C) may be transmitted through individual transmission paths without being wavelength multiplexed.

[0206] Fig. 46 is a diagram showing an example of the configuration of an optical access system 113. The optical access system 113 shown in Fig. 46 differs from the optical access system 101 shown in Fig. 34 in that it includes an optical GW 2013 instead of the optical GW 201. The optical GW 2013 differs from the optical GW 201 in that it does not include the wavelength multiplexer / demultiplexer 220 and the wavelength multiplexer / demultiplexer 243, and in that it includes the control device 235, wavelength multiplexer / demultiplexer 238, and monitoring device 265 shown in Fig. 44 instead of the control device 230 and monitoring device 260. The port of the optical SW 210 connected to the transmission path 503 outputs an upstream optical signal and inputs a downstream optical signal.

[0207] Furthermore, the branching unit 250a in the optical GW 2013 may have the configuration shown in Fig. 47. Fig. 47 is a diagram showing an example configuration of the optical access system 114. The optical GW 2014 of the optical access system 114 shown in Fig. 47 has a configuration similar to that of the branching unit 255 shown in Fig. 45, instead of the branching unit 250a included in the optical GW 2013 shown in Fig. 46.

[0208] (Fifth embodiment) This embodiment enables control of subscriber devices during communication. The following will mainly explain the differences from the above-described embodiment.

[0209] Fig. 48 is a diagram showing a configuration example of an optical access system 115. The optical access system 115 shown in Fig. 48 differs from the optical access system 104 shown in Fig. 37 in that the optical access system 115 includes an optical GW 2015 instead of the optical GW 204. The optical GW 2015 differs from the optical GW 204 in that a monitoring control device 267 is connected to the optical SW 211 instead of the monitoring device 265.

[0210] The monitor and control device 267 includes a tunable wavelength receiver 268 and a tunable wavelength transmitter 269. The monitor and control device 267 can receive an optical signal of any wavelength using the tunable wavelength receiver 268, and can transmit an optical signal of any wavelength using the tunable wavelength transmitter 269. The optical GW 2015 also includes a control device 235. As described in the first embodiment, when a subscriber device 40 is connected, the optical GW 2015 uses the control device 235 to perform connection processing (such as registration and wavelength allocation) for the subscriber device 40, and starts normal communication.

[0211] Now, consider a state in which the subscriber device 40-1 is connected to the ground B. The subscriber device 40-1 is in normal communication and cannot communicate with the control device 235. Therefore, by providing a monitor and control device 267 connected to the optical SW 211, a compact optical SW, it is possible to not only monitor the communication status of the subscriber device 40-1 but also to issue instructions for various settings for the subscriber device 40-1. Specifically, the optical signal split by the power splitter 251 is output to the optical SW 211 via the transmission path 555. The optical SW 211 outputs the received optical signal to the monitor and control device 267. The monitor and control device 267 monitors the optical signal received from the optical SW 211 by the tunable receiver 268 and also receives a control signal superimposed on the received optical signal. The tunable transmitter 269 of the monitor and control device 267 transmits a control signal to the subscriber device 40 as an optical signal. The optical SW 211 outputs the signal received from the tunable transmitter 269 to a port corresponding to the wavelength. The power splitter 251 multiplexes the control signal received from the optical SW 211 via the transmission line 556 with the optical signal transmitted on the transmission line 512. With this configuration, even when the subscriber device 40-1 is performing normal communication, it is possible to receive a connection destination change request from the subscriber device 40-1 and transmit a control signal to the subscriber device 40-1 to switch the wavelength.

[0212] For communication of control signals between the monitor and control device 267 and each subscriber device 40, a control signal that is slower than the optical main signal between the subscriber devices and can be superimposed on the main signal is used. For example, a technology such as AMCC can be used.

[0213] (Sixth embodiment) In this embodiment, electrical processing is performed on an optical signal extracted from an optical SW. The following will mainly explain the differences from the above-described embodiment.

[0214] Fig. 49 is a diagram showing an example of the configuration of an optical access system 116. The optical access system 116 shown in Fig. 49 differs from the optical access system 105 shown in Fig. 38 in that it includes an optical GW 2016 instead of the optical GW 202. The optical GW 2016 differs from the optical GW 202 in that an electrical processing unit 600 is connected to the optical GW 2016.

[0215] The electrical processing unit 600 converts an optical signal into an electrical signal, performs electrical processing, and then converts the signal back into an optical signal for output. The electrical processing unit 600 includes an O / E conversion unit 610, a processing execution unit 620, and an E / O conversion unit 630. The O / E conversion unit 610 corresponds to the O / E conversion unit 85 in FIG. 13. The O / E conversion unit 610 converts an optical signal input from the optical SW 210 into an electrical signal and outputs the electrical signal to the processing execution unit 620. The processing execution unit 620 corresponds to the processing execution unit 86 and the storage unit 88 in FIG. 13. The processing execution unit 620 performs electrical processing on the electrical signal converted by the O / E conversion unit 610 by a processor such as a CPU or accelerator reading and executing a program from a storage unit (not shown). This electrical processing includes an electrical signal processing function and an OLT function. The signal processing function is, for example, code error correction such as FEC. The E / O conversion unit 630 corresponds to the E / O conversion unit 87 in Fig. 13. The E / O conversion unit 87 converts the electrical signal into an optical signal and outputs it to the optical SW 210. The O / E conversion unit 610 and the E / O conversion unit 630 are, for example, a wavelength-tunable transceiver.

[0216] 49, the subscriber device 40-M is an ONU of a PON (Passive Optical Network). The subscriber device 40-M is connected to an optical GW 2016 via a transmission path 501 such as an optical fiber and a power splitter 507. An error correction function, an OLT function, etc. are implemented in a processing execution unit 620 of an electrical processing unit 600.

[0217] The wavelength control unit 310 notifies the processing execution unit 620 of the determination conditions for determining the signal to be electrically processed and the type of electrical processing to be performed on the signal. The processing execution unit 620 stores the information on the determination conditions and the type of electrical processing notified by the wavelength control unit 310.

[0218] For example, in step S5 of FIG. 33, the wavelength control unit 310 determines whether to perform electrical processing on the communication between the subscriber device 40 that has sent the connection request (hereinafter referred to as the requesting subscriber device 40) and the destination subscriber device 40. The wavelength control unit 310 determines whether to perform electrical processing and, if so, what type of electrical processing to perform, depending on the distance between the opposing requesting subscriber device 40 and the destination subscriber device 40, the services provided to the requesting subscriber device 40 or the destination subscriber device 40, etc. If the wavelength control unit 310 determines to perform electrical processing on the signal from the requesting subscriber device 40 addressed to the destination subscriber device 40 (hereinafter referred to as the transmitting signal electrical processing), it assigns a first transmitting wavelength and a second transmitting wavelength from among available wavelengths. Furthermore, if the wavelength control unit 310 determines to perform electrical processing on the signal from the destination subscriber device 40 addressed to the requesting subscriber device 40 (hereinafter referred to as the receiving signal electrical processing), it assigns a first receiving wavelength and a second receiving wavelength from among available wavelengths.

[0219] The first transmission wavelength is a wavelength for routing an optical transmission signal, which is an optical signal from the requesting subscriber device 40 and destined for the destination subscriber device 40, to the electrical processing unit 600. The second transmission wavelength is a wavelength for routing a transmission signal, which has been electrically processed by the electrical processing unit 600, to a port corresponding to the destination subscriber device 40. The first reception wavelength is a wavelength for routing a reception signal, which is an optical signal from the destination subscriber device 40 and destined for the requesting subscriber device 40, to the electrical processing unit 600. The second reception wavelength is a wavelength for routing a reception signal, which has been electrically processed by the electrical processing unit 600, to a port corresponding to the requesting subscriber device 40. The first transmission wavelength and the second transmission wavelength may be the same wavelength, or the first reception wavelength and the second reception wavelength may be the same wavelength.

[0220] When the wavelength control unit 310 determines that the transmission signal should be electrically processed, it sets information about the first transmission wavelength as the transmission wavelength in the wavelength instruction to be sent to the requesting subscriber device 40. When the wavelength control unit 310 determines that the reception signal should be electrically processed, it sets information about the second reception wavelength as the reception wavelength in the wavelength instruction to be sent to the requesting subscriber device 40.

[0221] When the OPS 300 determines to perform electrical processing of the transmitted signal, it instructs the destination subscriber device 40 to use the second transmission wavelength as the receiving wavelength. When the OPS 300 determines to perform electrical processing of the received signal, it instructs the destination subscriber device 40 to use the first transmission wavelength as the transmitting wavelength. For example, in the optical GW control unit 301 that controls the optical GW 200 that accommodates the destination subscriber device 40, the wavelength control unit 310 instructs the control device 230 to transmit a wavelength instruction that sets the receiving wavelength and transmitting wavelength of the destination subscriber device 40.

[0222] Furthermore, when it is determined that the transmit signal is to be electrically processed, the wavelength control unit 310 generates first instruction information that associates a determination condition for determining that the signal is a transmit signal from the requesting subscriber device 40 and addressed to the destination subscriber device 40, a type of transmit signal electrical processing to be performed on the transmit signal, a first transmission wavelength, and a second transmission wavelength. When it is determined that the receive signal is to be electrically processed, the wavelength control unit 310 generates second instruction information that associates a determination condition for determining that the signal is a receive signal from the destination subscriber device 40 and addressed to the requesting subscriber device 40, a type of receive signal electrical processing to be performed on the receive signal, a first reception wavelength, and a second reception wavelength. The wavelength control unit 310 transmits an electrical processing execution instruction that sets the generated first instruction information and second instruction information to the electrical processing unit 600.

[0223] When performing electrical processing of a transmission signal, the optical SW control unit 320 controls the optical SW 210 to output the transmission signal of the first transmission wavelength transmitted by the requesting subscriber device 40 to the electrical processing unit 600, and to output the transmission signal of the second transmission wavelength input from the electrical processing unit 600 to the transmission path 541 corresponding to the destination subscriber device 40. When performing electrical processing of a reception signal, the optical SW control unit 320 controls the optical SW 210 to output the reception signal of the first transmission wavelength input from the transmission path 542 corresponding to the destination subscriber device 40 to the electrical processing unit 600, and to output the reception signal of the second transmission wavelength input from the electrical processing unit 600 to the transmission path 522 corresponding to the requesting subscriber device 40.

[0224] For example, suppose that transmission signal electrical processing and reception signal electrical processing are performed on an optical signal between the subscriber device 40-2 and the destination subscriber device 40 of destination C. The transmission signal of a first transmission wavelength transmitted by the subscriber device 40-2 is output to the electrical processing unit 600 via the optical SW 210. The O / E conversion unit 610 converts the transmission signal input from the optical SW 210 into an electrical signal. The processing execution unit 620 refers to predetermined information contained in the converted electrical signal, and if it determines that the determination condition contained in the first instruction information is satisfied, performs transmission signal electrical processing on the transmission signal corresponding to the determination condition. For example, the processing execution unit 620 performs error correction such as FEC (forward error correction). The E / O conversion unit 630 converts the electrical signal that has been error corrected by the processing execution unit 620 into an optical signal of a second transmission wavelength indicated by the first instruction information, and outputs the optical signal to the optical SW 210. The optical SW 210 outputs the transmission signal of the second transmission wavelength to a transmission path 541 corresponding to destination C. By performing error correction, transmission characteristics are improved.

[0225] The optical SW 210 outputs a received signal of the first receiving wavelength input from the transmission path 542 corresponding to the destination subscriber device 40 of destination terminal C to the electrical processing unit 600. The O / E conversion unit 610 converts the received signal input from the optical SW 210 into an electrical signal. The processing execution unit 620 refers to predetermined information included in the transmitted signal converted into an electrical signal, and if it determines that the judgment condition included in the second instruction information is met, performs received signal electrical processing on the received signal corresponding to the judgment condition. The E / O conversion unit 630 converts the received signal, which is an electrical signal after the processing execution unit 620 has performed the received signal electrical processing, into an optical signal of the second receiving wavelength indicated by the second instruction information, and outputs the converted signal to the optical SW 210. The optical SW 210 outputs the transmitted signal of the second receiving wavelength to the transmission path 522 corresponding to the subscriber device 40-2.

[0226] 50 is a diagram showing an example of the configuration of the optical access system 116 when the electrical processing unit 600 multiplexes signals. The electrical processing unit 600 has a plurality of O / E conversion units 610, namely, O / E conversion units 610-1 and 610-2.

[0227] The upstream optical signal of subscriber device 40-3 and the upstream optical signal of subscriber device 40-M are connected to an electrical processing unit 600 via an optical SW 210. The electrical processing unit 600 is equipped with an OLT function. A processing execution unit 620 of the electrical processing unit 600 performs electrical stage processing of the OLT function. A plurality of subscriber devices 40 are connected to the OLT. The processing execution unit 620 equipped with the OLT function collectively manages the subscriber devices 40.

[0228] The O / E converter 610-1 converts the upstream optical signal of the subscriber device 40-3, input from the optical SW 210, into an electrical signal and outputs it to the processing execution unit 620. The O / E converter 610-2 converts the upstream optical signal of the subscriber device 40-M, input from the optical SW 210, into an electrical signal and outputs it to the processing execution unit 620. The processing execution unit 620 combines the upstream electrical signals transmitted from the subscriber devices 40-3 and 40-M into one signal and outputs it to the E / O converter 630. The E / O converter 630 converts the upstream electrical signal output by the processing execution unit 620 into an optical signal in accordance with a wavelength specified by the control device 230 and outputs it to the optical SW 210. The optical SW 210 outputs the upstream optical signal input from the electrical processing unit 600 to a transmission path 541 corresponding to destination C. In this way, the electrical processing unit 600 receives each of the multiple optical signals dropped by the optical gateway 2016, converts them into an electrical signal, multiplexes signals with the same destination using a multiplexing circuit, converts them back into an optical signal, and transmits them to the optical gateway 2016. This increases the transmission speed. Although Figures 49 and 50 show examples with one electrical processing unit, a configuration with multiple electrical processing units may also be used.

[0229] The power splitter 507 between the subscriber device 40 and the optical gateway 2016 may be a wavelength multiplexer / demultiplexer. For example, when the optical access system 116 is a WDM-PON, a wavelength demultiplexer is used between the subscriber device 40 and the optical gateway 2016.

[0230] (Seventh embodiment) In this embodiment, optical switches for different locations are ring-connected. The following description will focus on the differences from the above-described embodiment.

[0231] Fig. 51 is a diagram showing a configuration example of an optical access system 117. The optical access system 117 has a configuration in which three or more optical SWs 212 for different destinations are ring-connected via an optical communication network 30. In the example shown in Fig. 51, the optical access system 117 has a configuration in which an optical SW 212a which is an optical SW 212 for destination A, an optical SW 212b which is an optical SW 212 for destination B, and an optical SW 212c which is an optical SW 212 for destination C are ring-connected. A route between the optical SW 212a and the optical SW 212b in the optical communication network 30 is denoted as route P31, a route between the optical SW 212b and the optical SW 212c in the optical communication network 30 is denoted as route P32, and a route between the optical SW 212c and the optical SW 212a in the optical communication network 30 is denoted as route P33. Furthermore, one or more subscriber devices 40a are connected to the optical SW 212a, one or more subscriber devices 40b are connected to the optical SW 212b, and one or more subscriber devices 40c are connected to the optical SW 212c.

[0232] The optical SW or optical GW of the above-described embodiment is used as the optical SW 212. For example, the terminal B in Figures 6 to 10, 27, and 34 to 50 is assumed to be the terminal on the counterclockwise direction in the ring shown in Figure 51, and the terminal C in Figures 6 to 10, 27, and 34 to 50 is assumed to be the terminal on the clockwise direction in the ring shown in Figure 51. In this case, the optical SW 212a of the terminal A is connected to the optical SW 212b of the terminal B by the path P31, and the optical SW 212b of the terminal B is connected to the optical SW 212a of the terminal A by the path P32, the optical SW 212-c of the terminal C, and the path P33. The optical SW212a of terminal A is connected to the optical SW212c of terminal C via a path P33, and the optical SW212c of terminal C is connected to the optical SW212a of terminal A via a path P32, an optical SW212b of terminal B, and a path P31.

[0233] Therefore, with the counterclockwise connection from the optical SW212a of the terminal A to the optical SW212b of the terminal B as a backup system, a connection can also be made via a clockwise route from the optical SW212a of the terminal A to the optical SW212b of the terminal B via the optical SW212c of the terminal C, and the reverse route is also possible. Similarly, with the clockwise connection from the optical SW212a of the terminal A to the optical SW212c of the terminal C as a backup system, a connection can also be made via a counterclockwise route from the optical SW212a of the terminal A to the optical SW212b of the terminal B to the optical SW212c of the terminal C, and the reverse route is also possible.

[0234] In addition, as a backup system for the connection between subscriber devices 40a connected to optical SW212a for terminal A, it is also possible to use a counterclockwise route via route P31, optical SW212b for terminal B, route P32, optical SW212c for terminal C, and route P33, or a counterclockwise route via route P33, optical SW212c for terminal C, route P32, optical SW212b for terminal B, and route P31.

[0235] For example, in FIG. 14, the medium-distance line P2 may be a counterclockwise route around the ring, and the medium-distance line P3 may be a clockwise route around the ring. Also, any one of the destinations #1 to #q in FIG. 15 and FIG. 18 may be a counterclockwise destination, and another may be a clockwise destination. Also, when FIG. 25 and FIG. 26 show the optical SW1010 in one optical GW, any one of uplink #11 to uplink #43 may be a counterclockwise route around the ring, and another may be a clockwise route around the ring. Here, the route not selected as the ring route may be a ring route like the route selected as the ring route, or may be a diagonal line other than the ring, or may be connected to the subscriber device 40, or may be connected to another optical SW1010 shown in FIG. 25 and FIG. 26.

[0236] (Eighth embodiment) The optical access system of this embodiment has a function to stop the connection from a subscriber device to the optical gateway. The optical access system realizes this function by providing a shutter unit between the subscriber device and the optical SW included in the optical gateway, which switches between inputting and blocking the optical signal transmitted from the subscriber device to the optical SW. This allows the optical gateway to receive optical signals from subscriber devices that are permitted to communicate and to block optical signals from subscriber devices that are not permitted to communicate.

[0237] 52 is a configuration diagram of the optical access system 118. The optical access system 118 shown in Fig. 52 includes a control unit 302 and an optical gateway 2018. The optical gateway 2018 includes an optical switch 213, a shutter 591, and a WDM device 80.

[0238] The control unit 302 is the control unit 20 or the OSP 300 in the above-described embodiments. The control unit 302 has a wavelength management control unit 335 and an optical SW control unit 336. When the control unit 302 is the control unit 20 in the above-described embodiments, the wavelength management control unit 335 is the wavelength management control unit 25 in the above-described embodiments, and the optical SW control unit 336 is the optical SW control unit 26 in the above-described embodiments. When the control unit 302 is the OSP 300 in the above-described embodiments, the wavelength management control unit 335 is the wavelength control unit 310 and the control device 230 or the control device 235 in the above-described embodiments, and the optical SW control unit 336 is the optical SW control unit 320 in the above-described embodiments.

[0239] The optical SW 213 is the optical SW of the above-described embodiment. The optical SW 213 has ports 11-1-1 to 11-1-P (P is an integer equal to or greater than 2) and ports 11-2-1 to 11-2-Q (Q is an integer equal to or greater than 2). The port 11-1-p (p is an integer equal to or greater than 1 and equal to or less than P) is connected to the optical subscriber device 40 via a transmission path 50-1-p. The optical subscriber device 40 connected to the port 11-1-p is referred to as the optical subscriber device 40-p. The port 11-2-1 is connected to the wavelength management control unit 335. The ports 11-2-2, 11-2-3, 11-2-4, 11-2-5, ... are each connected to the WDM device 80 via a transmission path. The WDM device 80 multiplexes optical signals of different wavelengths output from ports 11-2-2, 11-2-3, 11-2-4, 11-2-5, ... by the optical SW213, and outputs the multiplexed optical signals to the multiplexed communication transmission path 90. The WDM device 80 also demultiplexes the optical signals received via the multiplexed communication transmission path 90 according to wavelength, and inputs each of the demultiplexed optical signals to ports 11-2-2, 11-2-3, 11-2-4, 11-2-5, ... of the optical SW213. Note that the optical GW2018 may not be provided with the WDM device 80, and ports 11-2-2, 11-2-3, 11-2-4, 11-2-5, ... of the optical SW213 may each be connected to the subscriber device 40 or an upper network via the transmission path 50-2.

[0240] The functions of passing and blocking optical signals in the optical GW 2018 will be described using FIG. 52. Each of the multiple subscriber devices 40 connected to the optical GW 2018 is assigned a wavelength corresponding to the communication destination. For example, each of the multiple subscriber devices 40 connected to the optical GW 2018 is assigned an individual wavelength. However, there may be a subscriber device 40 that is not authorized to connect to the optical GW 2018, such as when a malicious user connects to the network. In such a case, the optical signal of the subscriber device 40 that is not authorized to connect may collide with the optical signals of other subscriber devices 40, adversely affecting communications. Therefore, a shutter 591 is installed between the subscriber device 40 and the optical SW 213 in the optical GW 2018. In FIG. 52, the shutter 591 installed in the transmission path 50-1-p between the subscriber device 40-p and port 11-1-p of the optical SW 213 is denoted as shutter 591-p.

[0241] The shutter 591 is an example of a shutter unit that switches between inputting and blocking an optical signal transmitted from a subscriber device 40 to the optical SW 213. Any device can be used as the shutter 591 as long as it is capable of physically passing or blocking light. For example, an optical shutter such as a tunable filter or a variable optical attenuator can also be used as the shutter 591. By controlling the state of each shutter 591 to pass or block, the optical SW 13 can receive only optical signals from authorized subscriber devices 40. This prevents optical signals from malicious users.

[0242] Now, consider the case where a new subscriber device 40 is connected to the optical GW 2018. The new subscriber device 40 is first connected to the wavelength management control unit 335, which then assigns a wavelength to the new subscriber device 40 to be used for communication with the destination. Therefore, port 11-2-1, which is connected to the wavelength management control unit 335, is set as the connection destination of port 11-1, to which no subscriber device 40 is connected.

[0243] When a new subscriber device 40 is connected to port 11-1 of the optical SW 213, it outputs an optical signal requesting connection to request new registration from the optical GW 2018. If multiple subscriber devices 40 simultaneously output optical signals requesting connection with the same wavelength, a signal collision occurs in the wavelength management control unit 335.

[0244] In Figure 52, subscriber device 40-1 communicates with subscriber device 40 at destination B using an optical signal with wavelength λ1. The optical signal with wavelength λ1 output from subscriber device 40-1 passes through shutter 591-1 and is input to port 11-1-1. Optical SW213 outputs the optical signal input from port 11-1-1 to port 11-2-2. WDM device 80 multiplexes the optical signals output from ports 11-2-2, 11-2-3, ..., and outputs the multiplexed signal to multiplexed communication transmission path 90.

[0245] Meanwhile, suppose that a new subscriber device 40-2 is connected to port 11-1-2 of the optical SW 213 via transmission path 50-1-2, and a new subscriber device 40-3 is connected to port 11-1-3 of the optical SW 213 via transmission path 50-1-3. The subscriber devices 40-2 and 40-3 transmit optical signals with wavelength λ1 to request new registration. The connection destination for both ports 11-1-2 and 11-1-3 is the default port 11-2-1. If the subscriber devices 40-2 and 40-3 simultaneously output optical signals requesting connection with wavelength λ1, a signal collision occurs in the wavelength management control unit 335. This signal collision causes registration of the new subscriber devices 40-2 and 40-3 to fail.

[0246] Therefore, the state of the shutter 591 installed between the subscriber device 40 and the optical SW in the optical GW 2018 is controlled so that only one signal from the subscriber device 40 newly registered in the controller 302 is connected to the wavelength management controller 335 via the optical SW 213. For example, the shutter 591-2 is set to a state where optical signals pass, and the shutter 591-3 is set to a state where optical signals are blocked. Then, after the subscriber device 40-2 switches to the wavelength assigned by the wavelength management controller 335, the shutter 591-3 is set to a state where optical signals pass. This makes it possible to avoid collisions of optical signals in the wavelength management controller 335.

[0247] As described above, the port 11-1 of the optical SW 213 is initially connected to the wavelength management control unit 335. Therefore, if a malicious user were to connect to the port 11-1 in the initial state, the wavelength management control unit 335 could be attacked. Therefore, by controlling the states of the shutters 591, the initial port 11-1 of the optical SW 213 is prevented from receiving optical signals from unauthorized subscriber devices 40. For example, the shutters 591 corresponding to registered subscriber devices 40 and the shutters 591 corresponding to newly registered subscriber devices 40 are set to a passing state, and the other shutters 591 are set to a blocking state. Then, the optical SW 213 inputs an optical signal from the newly registered subscriber device 40 through the initial port 11-1 and controls the optical SW 213 to output the input optical signal from the port 11-2-1 to the wavelength management control unit 335. This prevents optical signals from malicious users.

[0248] To perform the above control, the control unit may be provided with a shutter control unit that controls each shutter, as shown in Fig. 53. This allows each shutter to be controlled externally.

[0249] Fig. 53 is a configuration diagram of an optical access system 119. In the optical access system 119 shown in Fig. 53, the same components as those in the optical access system 118 shown in Fig. 52 are assigned the same reference numerals, and their description will be omitted. The optical access system 119 differs from the optical access system 118 shown in Fig. 52 in that it includes a control unit 303 instead of the control unit 302. The control unit 303 differs from the control unit 302 shown in Fig. 52 in that it further includes a shutter control unit 337. Providing the shutter control unit 337 makes it possible to externally control a shutter 591.

[0250] The shutter control unit 337 shares various information such as subscriber information with other control function units in the control unit 303. When a new subscriber device 40-p is connected, the shutter control unit 337 controls the shutter 591-p corresponding to that subscriber device 40-p to change from a blocking state to a passing state based on the subscriber information and the like registered in the control unit 303. As a result, when a new subscriber device 40 is connected, the shutter control unit 337 controls the shutter 591 corresponding to the new subscriber device 40, in addition to the shutters 591 corresponding to the registered subscriber devices 40, to change the passing state and the other shutters 591 to a blocking state.

[0251] Furthermore, when multiple subscriber devices 40 simultaneously newly connect to the optical gateway 2019, the shutter control unit 337 determines the order of the subscriber devices 40 based on the priority of each of the subscriber devices 40 and the distance from each of the subscriber devices 40 to the optical gateway 2019. For example, if the logical condition, such as priority, is the same, the shutter control unit 337 determines the order based on the physical condition, such as distance. In accordance with the determined order, the shutter control unit 337 controls the state of the shutter 591 corresponding to each of the subscriber devices 40 to change from a blocked state to a passing state for a certain period of time. The subscriber device 40 newly connecting to the optical gateway 2019 continuously outputs a connection request optical signal at regular intervals. As a result, the connection request optical signal transmitted when the shutter 591 is in the passing state is output to the wavelength management control unit 335.

[0252] Even if the wavelength management control unit 335 has a function of wavelength tunable selective reception, if the wavelengths of the optical signals output from the multiple subscriber devices 40 newly connected to the optical SW 213 are the same, a signal collision will occur in the wavelength management control unit 335. Therefore, the shutter 591 is necessary.

[0253] The shutter 591 may also have a photodetection function. For example, the shutter 591 includes a photodetector for detecting light. The shutter 591 uses the photodetection function to detect an optical signal from a subscriber device 40 newly connected to the transmission path 50-1 and notify the control unit 302. The shutter 591 may notify the control unit 302 when it detects light of a predetermined intensity or higher, or may notify the control unit 302 of the received light intensity. The optical switch control unit 336 of the control unit 302 controls the optical switch 213 to connect the subscriber device 40 corresponding to the shutter 591 to the wavelength management control unit 335, thereby performing an initial connection operation. Alternatively, if the shutter control unit 337 determines that the photodetector of the shutter 591 has detected an excessively strong optical signal, the shutter 591 can be placed in a blocking state to block the optical signal as an abnormal signal. An excessively strong optical signal is, for example, a level that could damage components such as the optical switch 213 or cause signal degradation due to nonlinear optical effects.

[0254] In addition, if a connection of a new subscriber device 40 is detected even though registration information such as subscriber information is not registered in the control unit 302, i.e., even though the subscriber device 40 is not scheduled to be connected to the optical GW, the shutter control unit 337 can determine that the connection is by a malicious user and take measures such as closing the shutter 591. For example, information about the newly connected subscriber device 40 is registered in advance in the control unit 302. This information includes information about the port 11-1 corresponding to the newly connected subscriber device 40 and information about the period during which the new connection will be made. When an optical signal is detected, the photodetector of the shutter 591-p notifies the control unit 302 of the detection. The shutter control unit 337 identifies the port 11-1-p corresponding to the shutter 591-p that sent the notification. If there is no registration information about the newly connected subscriber device 40 to that port 11-1-p at the time of receiving the notification, the shutter control unit 337 determines that the connection is by a malicious user. In this case, the shutter control unit 337 closes the shutter 591-p that sent the notification.

[0255] Furthermore, if possible in principle, the optical signal can be blocked even if the port 11-1 of the optical switch is left open and not connected to anything.

[0256] The optical GW 2018 and the optical GW 2019 may be provided with a shutter device 592 shown in FIG. 54 instead of the shutter 591. FIG. 54 is a diagram showing an example of the configuration of the shutter device 592. The shutter device 592 includes a wavelength multiplexer / demultiplexer 593, F shutters 594 (F is an integer of 2 or more), and a wavelength multiplexer / demultiplexer 595. The F shutters 594 are respectively referred to as shutters 594-1 to 594-F. The wavelength multiplexer / demultiplexer 593 divides the optical signals received from the subscriber device 40 into wavelengths λ1 to λ2. F The shutter 594-f (f is an integer between 1 and F) separates the wavelengths λ 1 and λ 2 separated by the wavelength multiplexer / demultiplexer 593 and outputs the separated optical signal. f The shutter 594 can be the same device as the shutter 591. The wavelength multiplexer / demultiplexer 595 multiplexes the optical signals transmitted by the shutters 594-1 to 594-F, and outputs the multiplexed optical signals to the optical SW213.

[0257] It is possible to transmit or block optical signals of one or more desired wavelengths by means of the shutter device 592. The shutter device 592 must be provided with shutters 594 in the number corresponding to the number of wavelengths to be used.

[0258] Each shutter 594 may be equipped with a light detection function similar to the above-described shutter 591. When the shutter 594 detects light, it notifies the control unit 302 or the control unit 303 of the detection of light. The optical SW control unit 336 identifies the shutter device 592 equipped with the shutter 594-f that is the sender of the notification and the shutter device 592 equipped with the wavelength λ corresponding to the shutter 594-f that is the sender of the communication. f The wavelength management control unit 335 transmits the identified wavelength λ from the subscriber device 40 connected to the identified shutter device 592. fThe wavelength management control unit 335 determines whether transmission of the optical signal at the wrong wavelength is permitted. This allows the wavelength management control unit 335 to detect the signal if the subscriber device 40 outputs an optical signal at an incorrect wavelength. The wavelength management control unit 335 can also re-transmit a wavelength setting signal to the subscriber device 40 that has output an optical signal at an incorrect wavelength, thereby resetting the wavelength.

[0259] On the other hand, the shutter device 592 is also effective when the subscriber device 40 uses multiple wavelengths. For example, when the subscriber device 40 uses wavelengths λ1 and λ2, the corresponding shutters 594-1 and 594-2 are opened, and the other shutters 594-3 to 594-F are closed. This prevents signals of other wavelengths from entering and makes it possible to limit the wavelengths that can be used by the user. Furthermore, when the subscriber device 40 starts using a new wavelength, for example, wavelength λ3, the corresponding shutter 594-3 is opened. This allows the subscriber device 40 to start using an optical signal (optical service) using the new wavelength.

[0260] Furthermore, the optical gateway 2018 and the optical gateway 2019 may be provided with a shutter device 596 shown in FIG. 55 instead of the shutter 591. FIG. 55 is a diagram showing an example of the configuration of the shutter device 596. The shutter device 596 includes the shutter 591, a controlled wavelength demultiplexer 597, and a shutter controller 598. The controlled wavelength demultiplexer 597 separates the wavelength λ used for controlling the shutter controller 598 from the signal output by the optical switch 213. c The optical signal of wavelength λ is used to control the shutter controller 598. c The optical signal is transmitted from the control unit 302 or the control unit 303. c are wavelengths not used for communication with the subscriber unit 40. The controlled wavelength demultiplexer 597 demultiplexes the separated wavelengths λ c to the shutter controller 598, and outputs an optical signal of wavelength λ c The remaining optical signal obtained by separating the optical signal from the control wavelength demultiplexer 597 is output to the shutter 591. The shutter controller 598 controls the shutter 591 to be in a transmitting state or a blocking state based on the optical signal separated by the control wavelength demultiplexer 597.

[0261] Furthermore, TDM (time division multiplexing) communication becomes possible by the optical access system 118 shown in Fig. 52 or the optical access system 119 shown in Fig. 53. Fig. 56 is a diagram for explaining the operation of the optical access system 118 when performing TDM communication. An example in which a plurality of subscriber devices 40-1 to 40-3 communicate with a subscriber device 40b at destination B will be explained using Fig. 56.

[0262] In FIG. 56, the subscriber devices 40-1, 40-2, and 40-3 are performing TDM communication with a subscriber device 40b connected to an optical gateway of another destination, for example, destination B, via the optical gateway 2018. That is, the subscriber device 40b transmits and receives signals to and from each of the subscriber devices 40-1, 40-2, and 40-3 as burst signals. It is necessary to prevent collisions between the optical signals transmitted from the subscriber devices 40-1, 40-2, and 40-3 to the subscriber device 40b. Therefore, when the subscriber device 40-1 communicates with the subscriber device 40b, the shutter 591-1 is set to a passing state, and the shutters 591-2 and 591-3 are set to a blocking state. This prevents the subscriber devices 40-2 and 40-3 from communicating with the subscriber device 40b. Next, when the subscriber device 40-2 communicates with the subscriber device 40b, the shutter 591-2 is set to a passing state, and the shutters 591-1 and 591-3 are set to a blocking state. As a result, subscriber devices 40-1 and 40-3 cannot communicate with subscriber device 40b. Next, when subscriber device 40-3 communicates with subscriber device 40b, shutter 591-3 is set to the passing state, and shutters 591-1 and 591-2 are set to the blocking state. As a result, subscriber devices 40-1 and 40-2 cannot communicate with subscriber device 40b.

[0263] As described above, among the shutters 591 corresponding to the subscriber devices 40 communicating with the same destination, the shutters 591 corresponding to the subscriber devices 40 at the communication timing are set to a passing state, and the shutters 591 corresponding to the subscriber devices 40 not at the communication timing are set to a blocking state. This physically blocks the subscriber devices 40 from communicating at the communication timing. In the optical access system 119, the shutter control unit 337 switches between the blocking and passing states of each shutter 591. Furthermore, if the GW 2018 is equipped with a shutter device 592 instead of the shutter 591, it switches between the blocking and passing states of the optical signals of the wavelengths used by the subscriber devices 40 to communicate with the same destination as other subscriber devices 40. In this way, the shutter units corresponding to multiple subscriber devices 40 with the same destination transmit optical signals transmitted from those subscriber devices 40 and input them to the optical SW 213 at different times so as not to overlap. This prevents signal collisions between the subscriber devices 40.

[0264] In this embodiment, the shutter is disposed inside the optical gateway as an example of where to place the shutter, but the shutter may be installed outside the optical gateway (for example, between the subscriber device and the optical gateway), or the shutter may be disposed inside the subscriber device.

[0265] Furthermore, in this embodiment, instead of providing a shutter, the optical access system may be configured to be able to control an optical switch so as to output an optical signal to be blocked to a terminal device that terminates the optical signal, as shown in FIG.

[0266] FIG. 57 is a configuration diagram of the optical access system 120. The optical access system 120 shown in FIG. 57 includes a control unit 302 and an optical gateway 2020. The optical gateway 2020 includes an optical SW 213, a WDM device 80, and a reflectionless termination device 599. The optical gateway 2020 may not include the WDM device 80, and ports 11-2-2, 11-2-3, 11-2-4, 11-2-5, ... of the optical SW 213 may be connected to the subscriber device 40 or an upper network via a transmission path 50-2. One or more ports 11-2 of the optical SW 213 are connected to the reflectionless termination device 599. In FIG. 57, ports 11-2-(Q-1) and 11-2-Q are connected to the reflectionless termination device 599. The reflectionless termination device 599 terminates the input optical signal and does not output the optical signal.

[0267] When communication between the subscriber devices 40-2 and 40-3 is not permitted, the optical SW control unit 336 controls the optical SW 2020 to output the optical signal input from port 11-1-2 to port 11-2-(Q-1) and the optical signal input from port 11-1-3 to port 11-2-Q. In this way, the optical GW 2020 blocks the optical signals received from the subscriber devices 40-2 and 40-3 so that they do not affect the communication of other subscriber devices 40.

[0268] Furthermore, a photodetector having a photodetection function may be implemented in the port 11-1 on the subscriber device side of the optical SW 213, or between the subscriber device 40 and the optical SW 213. When the photodetector detects light, it notifies the control unit 302 of the detection. The optical SW control unit 336 identifies the port 11-1 in which the photodetector that sent the notification is implemented or connected. If the optical SW control unit 336 determines that the identified port 11-1 is not the port 11-1 connected to the subscriber device 40 for which communication is permitted, it controls the optical SW 213 to output the signal input from the identified port 11-1 to the port 11-2 connected to the reflectionless termination device 599.

[0269] This section explains the superposition of an AMCC signal onto a main signal. In the optical domain, the AMCC signal and the main signal use the same wavelength. The main signal is, for example, a CPRI (Common Public Radio Interface) signal, such as a 10 Gb / s (Gigabits per second) OOK (On-off keying) signal. The AMCC signal is transmitted by superimposing a 1 MHz carrier wave onto the main signal, and conveys information by intensity modulation. In this way, the low-speed AMCC signal is superimposed on the main signal, and the superimposed AMCC signal can be separated from the main signal.

[0270] In the electrical domain, the AMCC signal and the main signal use different frequencies. The AMCC signal has a narrower bandwidth than the main signal. For example, a power combiner combines a 10 GHz electrical main signal with a 1 MHz electrical AMCC signal, and a transmitter converts this combined signal into an optical signal to generate a main signal with an AMCC signal superimposed on it. Note that the carrier frequency may be another frequency, such as 500 kHz, that does not overlap with the electrical main signal, and other modulation methods, such as phase modulation, may also be used.

[0271] The above-described control devices 230 and 235, monitoring devices 260 and 265, monitoring control device 267, wavelength control unit 310, and optical SW control unit 320 may each include a central processing unit (CPU), memory, auxiliary storage device, etc., connected via a bus, and may execute a program to realize some or all of the above-described functions. Note that some or all of the functions of the control devices 230 and 235, monitoring devices 260 and 265, monitoring control device 267, wavelength control unit 310, and optical SW control unit 320 may be realized using hardware such as an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a field-programmable gate array (FPGA). The programs for the control devices 230 and 235, monitoring devices 260 and 265, monitoring control device 267, wavelength control unit 310, and optical SW control unit 320 may be recorded on a computer-readable recording medium. Examples of the computer-readable recording medium include portable media such as magneto-optical disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into a computer system. The program may be transmitted via a telecommunications line.

[0272] Furthermore, the wavelength control unit 310 and the optical SW control unit 320 may be implemented using one information processing device, or may be implemented using multiple information processing devices that are communicably connected via a network.

[0273] According to the above-described embodiment, the optical communication device includes an optical SW, a wavelength management controller, and an optical SW controller. The optical SW is connected to multiple transmission paths and outputs an optical signal input from one of the transmission paths to another transmission path. The wavelength management controller assigns a wavelength to a subscriber device according to the communication destination. The optical SW controller controls the optical SW so that the optical signal transmitted from the subscriber device to which the wavelength is assigned is output to a transmission path according to a forwarding destination on the path from the subscriber device to the communication destination. In this manner, the optical SW distributes the output destination of the optical signal according to the path. Note that the communication destination is, for example, another subscriber device opposite the subscriber device to which the wavelength is assigned. Furthermore, the forwarding destination is various devices and various functional units on the path from the subscriber device to the opposite subscriber device, such as the opposite subscriber device, a controller, an electrical signal processor, a power splitter (e.g., a coupler), etc.

[0274] The optical SW control unit controls the optical SW to output an optical signal input from the transmission path to a transmission path corresponding to a destination specified by a combination of the subscriber device that transmitted the optical signal and the wavelength of the optical signal. Alternatively, the optical SW control unit controls the optical SW to output the optical signal to a port connected to a transmission path corresponding to a destination specified by a combination of the subscriber device that transmitted the optical signal, the wavelength of the input optical signal, and the port to which the optical signal was input. Alternatively, the optical SW control unit controls the optical SW only by the input port and the subscriber device to output the optical signal to a port connected to a transmission path corresponding to a destination specified by a combination of the input port and wavelength if the wavelength and the subscriber device have a unique relationship in the optical SW.

[0275] According to the above-described embodiment, it is possible to set the transceiver of the subscriber device to use a route according to the destination, and to relay a signal transmitted from the subscriber device using that route according to the destination. Furthermore, after the initial setting of the subscriber device, it is possible to relay an optical signal according to the destination with less delay than before.

[0276] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configurations are not limited to these embodiments, and include designs within the scope of the present invention that do not deviate from the gist of the present invention. [Explanation of symbols]

[0277] 1...Optical communication system, 10, 10a, 10b, 10c, 10d, 10e, 10f, 10g, 34, 95a-1, 95a-2, 95b-1, 95b-2, 96a-1, 96a-2, 96b-1, 96b-2, 210, 211, 212a, 212b, 212c, 213, 1001, 1002, 1003, 1004, 1005, 1006, 1007, 1008, 1009a, 1009b, 1010-1 to 1010-4...optical switches, 11-1, 11-1-1~11-1-P, 11-2, 11-2-1~11-2-Q...Port, 20, 302, 303...control unit, 21, 41, 411, 412...Optical transceiver, 22, 42, 237...Optical transmitter, 23, 43, 232, 236...Optical receiver, 25, 335...wavelength management control unit, 26, 320, 336...optical switch control unit, 30...Optical communication network, 31...WDM access ring network, 32-1~32-4...Add / Drop node, 33...Demultiplexing section, 35...combining section, 40, 40-1~40-M, 40a-1~40a-3, 40b-1~40b-3, 40c-1~40c-3, 40a-1-1, 40a-1-2, 40-p-1~40-p-Np, 40-pN, 40-p~40-(p+N)...Subscriber equipment, 46-1, 46-3...User, 46-2...Mobile base station, 50, 50-1, 50-2, 50-1-p~50-1-(p+N), 50-1-p1~50-1-pN, 50-1-p-1~50-p-Np, 50-2-1~50-2-q, 50-2-(N- 1), 50-2-N, 50-2-q-1~50-2-qN, 50-2-(1+N), 53, 54a, 54b, 54c, 54d, 92, 93-1~93-N, 501, 503, 504, 511, 5 12, 521, 522, 531, 533, 534, 540, 541, 542, 543-1, 543-2, 544, 545, 546, 547, 548, 549, 551, 551a, 552, 552b, 555, 560, 561, 562, 563, 570, 571, 572, 573, 574, 575, 581, 582, 583, 584, 585, 586, 587, 588, 589...transmission path, 51, 73...folded transmission line, 55, 55-1, 55-2, 55-p, 55-(p+1), 56, 57a, 57b, 61, 66, 69, 71, 72, 251, 251a, 251b, 252, 252b, 254, 258, 259, 270, 271, 272, 273, 502, 507... Power splitter, 58, 59...distribution section, 60, 65...monitoring circuit, 67, 68, 80, 80a, 80b, 81, 89, 97...WDM equipment, 82a-1, 82a-2, 82b-1, 82b-2, 241, 247...Multiplexer, 83a-1, 83a-2, 83b-1, 83b-2, 242, 248... splitter, 85...O / E conversion section, 86...Processing execution unit, 87...E / O conversion unit, 88...Memory section, 90, 91...Multiplex communication transmission line, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120...Optical access systems, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2018, 2019, 2020... Optical Gateway, 220, 238, 243, 244, 245, 249, 256, 257, 593, 595...Wavelength multiplexer / demultiplexer, 230...control device, 231, 261...wavelength demultiplexer, 233, 269...Tunable wavelength transmitter, 235...control device, 250, 250a, 250b, 253, 255...branching section, 260, 265...monitoring device, 262...optical receiver, 266...Tunable wavelength optical receiver, 267...Monitoring and control equipment, 268...Tunable wavelength receiver, 300...Operation System, 301...Optical GW control unit, 310...wavelength control section, 337...shutter control unit, 350...Administrative database, 452...Tunable wavelength filter, 453...Receiver, 454...WDM filter, 591-1~591, 594-1~594-m...Shutters, 592, 596...Shutter device, 597...Controlled wavelength demultiplexer, 598...Shutter controller, 599...Reflection-free termination device, 84, 600...electrical processing section, 861...processor, 862...Accelerator

Claims

1. An optical communication system that performs optical transmission between subscriber devices and relays optical signals according to their destinations, a control unit that communicates with the subscriber device using control signals; an access control unit that grants permission for main signal communication to the subscriber device; an add-drop unit that inputs an optical signal from the subscriber device and outputs an optical signal to the subscriber device; a multiplexing / demultiplexing unit that concentrates optical paths from the subscriber device to another path in the upstream direction and distributes optical paths from the other path to the subscriber device in the downstream direction; An optical communication system comprising:

2. the optical communication system includes an optical communication device having the add / drop unit, the add / drop unit has an add unit that inputs an optical signal from the subscriber device and a drop unit that outputs an optical signal to the subscriber device, the optical communication device further comprises a return transmission line connected to the add unit that receives an optical signal from the subscriber device and the drop unit that outputs an optical signal to another subscriber device, the return transmission line performing return communication; 2. The optical communication system according to claim 1.

3. The control signal is superimposed on a main signal.

2. The optical communication system according to claim 1.

4. The access control unit checks, based on the optical signal transmitted from the subscriber device, whether the wavelength designated for the subscriber device is correctly set or whether the output power is sufficient, and when it is confirmed that there is no problem, allows the subscriber device to start main signal communication.

2. The optical communication system according to claim 1.

5. the demultiplexing unit multiplexes the optical signals of different wavelengths from a plurality of subscriber devices and outputs the multiplexed signals to a transmission line between the multiplexed signals and the other path of the destination; the demultiplexing unit inputs an optical signal transmitted from the other path of the destination from the transmission line; and demultiplexes the input optical signal into signals addressed to the subscriber devices according to wavelength.

2. The optical communication system according to claim 1.

6. the add / drop unit has a plurality of subscriber device side ports and a plurality of network side ports; the return transmission line connects some of the plurality of network-side ports; the add unit receives an optical signal from the subscriber device side port connected to the subscriber device, and outputs the received optical signal to the network side port connected to the return transmission line; the drop unit receives the optical signal transmitted through the return transmission line from another of the network-side ports connected to the return transmission line, and outputs the received optical signal to the subscriber equipment-side port connected to the other subscriber equipment.

3. The optical communication system according to claim 2.

7. the add / drop unit has a plurality of subscriber device side ports and a plurality of network side ports; the return transmission line connects some of the plurality of network-side ports; The optical communication device performs a process in which the add unit multiplexes the optical signals input from the subscriber equipment side ports connected to each of the plurality of subscriber equipment, and outputs the multiplexed optical signals to the network side port connected to the return transmission line, and a process in which the add unit inputs the optical signals transmitted through the return transmission line from another of the network side ports connected to the return transmission line, branches the input optical signals, and outputs the branched optical signals from the drop unit to the subscriber equipment side ports connected to each of the plurality of other subscriber equipment.

3. The optical communication system according to claim 2.

8. the add / drop unit inputs and outputs multiplexed optical signals of multiple wavelengths; 2. The optical communication system according to claim 1.

9. An optical communication device that performs optical transmission between a subscriber device and the optical signal and relays the optical signal according to the destination, a superimposing unit for superimposing a control signal for the control device to communicate with the subscriber device on a main signal; an access control unit that grants permission for main signal communication to the subscriber device or grants the permission based on an instruction from the control unit; an add-drop unit that inputs an optical signal from the subscriber device and outputs an optical signal to the subscriber device; a multiplexing / demultiplexing unit that concentrates optical paths from the subscriber device to another path in the upstream direction and distributes optical paths from the other path to the subscriber device in the downstream direction; An optical communication device comprising:

10. the add / drop unit has an add unit that inputs an optical signal from the subscriber device and a drop unit that outputs an optical signal to the subscriber device, the optical communication device further comprises a return transmission line connected to the add unit that receives an optical signal from the subscriber device and the drop unit that outputs an optical signal to another subscriber device, the return transmission line performing return communication; 10. The optical communication device according to claim 9.

11. The access control unit checks, based on the optical signal transmitted from the subscriber device, whether the wavelength designated for the subscriber device is correctly set or whether the output power is sufficient, and when it is confirmed that there is no problem, it permits the subscriber device to start main signal communication, or it permits the subscriber device to start main signal communication based on an instruction from the control device.

10. The optical communication device according to claim 9.

12. the demultiplexing unit multiplexes the optical signals of different wavelengths from a plurality of subscriber devices and outputs the multiplexed signals to a transmission line between the multiplexed signals and the other path of the destination; the demultiplexing unit inputs an optical signal transmitted from the other path of the destination from the transmission line; and demultiplexes the input optical signal into signals addressed to the subscriber devices according to wavelength.

10. The optical communication device according to claim 9.

13. the add / drop unit has a plurality of subscriber device side ports and a plurality of network side ports; the return transmission line connects some of the plurality of network-side ports; the add unit receives an optical signal from the subscriber device side port connected to the subscriber device, and outputs the received optical signal to the network side port connected to the return transmission line; the drop unit receives the optical signal transmitted through the return transmission line from another of the network-side ports connected to the return transmission line, and outputs the received optical signal to the subscriber equipment-side port connected to the other subscriber equipment. The optical communication device according to claim 10.

14. the add / drop unit has a plurality of subscriber device side ports and a plurality of network side ports; the return transmission line connects some of the plurality of network-side ports; The optical communication device performs a process in which the add unit multiplexes the optical signals input from the subscriber equipment side ports connected to each of the plurality of subscriber equipment, and outputs the multiplexed optical signals to the network side port connected to the return transmission line, and a process in which the add unit inputs the optical signals transmitted through the return transmission line from another of the network side ports connected to the return transmission line, branches the input optical signals, and outputs the branched optical signals from the drop unit to the subscriber equipment side ports connected to each of the plurality of other subscriber equipment. The optical communication device according to claim 10.

15. the add / drop unit inputs and outputs multiplexed optical signals of multiple wavelengths; 10. The optical communication device according to claim 9.

16. a control unit that communicates with the subscriber device using a control signal so that the subscriber device can be connected to the optical communication device and transmit and receive optical signals to and from a communication destination via a transmission line; an access control unit that grants permission for main signal communication to the subscriber device; A control device comprising:

17. The access control unit checks, based on the optical signal transmitted from the subscriber device, whether the wavelength designated for the subscriber device is correctly set or whether the output power is sufficient, and when it is confirmed that there is no problem, allows the subscriber device to start main signal communication. The control device of claim 16.

18. An optical communication method executed by an optical communication system that performs optical transmission between a subscriber device and an optical signal and relays the optical signal according to its destination, comprising: a control step of communicating with said subscriber device using control signals; an access control step of granting permission for main signal communication to the subscriber device; an add-drop step of inputting an optical signal from the subscriber device and outputting an optical signal to the subscriber device; a demultiplexing step of concentrating optical paths from the subscriber device to another path in the upstream direction and distributing optical paths from the other path to the subscriber device in the downstream direction; An optical communication method comprising:

19. An optical communication method executed by an optical communication device that performs optical transmission between a subscriber device and the optical communication device and relays an optical signal according to a destination, comprising: a superimposing step in which a control device superimposes a control signal for communication with the subscriber device on a main signal; an access control step of granting permission for main signal communication to the subscriber device or granting the permission based on an instruction from the control device; an add-drop step of inputting an optical signal from the subscriber device and outputting an optical signal to the subscriber device; a demultiplexing step of concentrating optical paths from the subscriber device to another path in the upstream direction and distributing optical paths from the other path to the subscriber device in the downstream direction; An optical communication method comprising:

20. a control step of connecting a subscriber device to an optical communication device and communicating with the subscriber device using a control signal so as to transmit and receive optical signals to and from a communication destination via a transmission line; an access control step of granting permission for main signal communication to the subscriber device; An optical communication control method comprising:

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